CWE-407

{
  "affected": [],
  "aliases": [
    "CVE-2024-11828"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-11-26T19:15:22Z",
    "severity": "MODERATE"
  },
  "details": "A denial of service (DoS) condition was discovered in GitLab CE/EE affecting all versions from 13.2.4 before 17.4.5, 17.5 before 17.5.3, and 17.6 before 17.6.1. By leveraging this vulnerability an attacker could create a DoS condition by sending crafted API calls. This was a regression of an earlier patch.",
  "id": "GHSA-rmhm-cwgp-268p",
  "modified": "2024-11-26T21:32:24Z",
  "published": "2024-11-26T21:32:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-11828"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/2380264"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.com/gitlab-org/gitlab/-/issues/443559"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

{
  "affected": [],
  "aliases": [
    "CVE-2023-30421"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-04-19T22:15:14Z",
    "severity": "LOW"
  },
  "details": "mystrtod in mjson 1.2.7 requires more than a billion iterations during processing of certain digit strings such as 8891110122900e913013935755114.",
  "id": "GHSA-rqfj-9wmv-vpgp",
  "modified": "2025-04-20T00:31:40Z",
  "published": "2025-04-20T00:31:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-30421"
    },
    {
      "type": "WEB",
      "url": "https://github.com/boofish/json_bugs/blob/main/mjson"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cesanta/mjson/releases"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.0.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "linkify-it"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-59887"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-21T19:06:09Z",
    "nvd_published_at": "2026-07-08T17:17:26Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n`linkify-it`\u0027s schema-scan loop (`.test()` / `.match()`, the documented public API) invokes the `mailto:`\nschema validator at **every** `mailto:` occurrence in the input text. For each occurrence the validator does\n`text.slice(pos)` (an O(n) copy) and runs an email regex whose local-part class `src_email_name` greedily\nscans the **entire remaining tail** (O(n)) before failing. With N `mailto:` occurrences that is\n**N \u00d7 O(n) = O(n\u00b2)**. Because linkify-it runs on arbitrary user text (markdown-it feeds it whole documents\nwhen `linkify:true`), an unauthenticated attacker can block the single-threaded event loop for many seconds\nwith a small input. No length bound (unlike an HTTP header).\n\n### Root cause \u2014 `index.mjs` + `lib/re.mjs`\n```js\n// index.mjs (mailto validator) \u2014 runs at every \"mailto:\" hit\n\u0027mailto:\u0027: { validate: function (text, pos, self) {\n  const tail = text.slice(pos)                                  // O(n) copy per hit\n  if (!self.re.mailto) self.re.mailto = new RegExp(\u0027^\u0027 + self.re.src_email_name + \u0027@\u0027 + self.re.src_host_strict, \u0027i\u0027)\n  if (self.re.mailto.test(tail)) { ... }                        // scans the whole O(n) tail\n  return 0\n}}\n// lib/re.mjs:91-93 \u2014 every char of \"mailto:\" (incl. \u0027:\u0027,\u0027-\u0027,\u0027;\u0027) is in this class:\nre.src_email_name = \u0027[\\\\-;:\u0026=\\\\+\\\\$,\\\\.a-zA-Z0-9_][\\\\-;:\u0026=\\\\+\\\\$,\\\\\"\\\\.a-zA-Z0-9_]*\u0027\n```\nThe `while ((m = re.exec(text)) !== null) { \u2026testSchemaAt\u2026 }` scan loop calls the validator at each\n`mailto:` hit; `src_email_name` greedily consumes the whole tail (all chars are in its class) then fails for\nlack of `@`. `http:`/`https:` do NOT blow up \u2014 their validator requires the tail to start with `//`, failing\nin O(1) per hit.\n\n### Proof of Concept (confirmed, linkify-it 5.0.1, Node v24)\n```js\nconst LinkifyIt = require(\u0027linkify-it\u0027);\nconst lf = new LinkifyIt();\nlf.match(\u0027mailto:\u0027.repeat(48000));   // ~336 KB of \"mailto:mailto:\u2026\" -\u003e seconds of blocked event loop\n```\n| input (same bytes) | 56 KB | 112 KB | 224 KB | 336 KB |\n|---|---:|---:|---:|---:|\n| **`mailto:` contiguous** | 97 ms | 357 ms | 1438 ms | 3272 ms |\n| `mailto:` space-separated | 2 ms | 3 ms | 5 ms | 8 ms |\n| `http://` contiguous | 12 ms | 17 ms | 33 ms | 49 ms |\n\n\u00d7~4 per 2\u00d7 input \u21d2 O(n\u00b2); equal-byte controls stay flat \u21d2 algorithmic, not a GC/allocation artifact.\nReal-world via markdown-it 14.x (`{linkify:true}`), `md.render(\u0027mailto:\u0027.repeat(n))`: 219 KB \u2248 ~5 s.\n\u003cimg width=\"737\" height=\"161\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b5d390f3-68d0-4861-9c47-ad8aff0203d5\" /\u003e\n\n### Impact\nReachable on arbitrary user text via the documented `.test()`/`.match()` API and through markdown-it\u0027s\nlinkifier \u2014 comment systems, chat, forums, wikis, note apps that render user markdown with linkify enabled.\nA ~220 KB post hangs the event loop ~5 s; a few hundred KB \u2192 tens of seconds. Availability only.\n\n### Suggested remediation\nBound the email local-part per RFC 5321 (\u226464) so per-hit work is O(1), and avoid the full-tail slice:\n```js\n// lib/re.mjs \u2014 cap the greedy run:\nre.src_email_name = \u0027[\\\\-;:\u0026=\\\\+\\\\$,\\\\.a-zA-Z0-9_][\\\\-;:\u0026=\\\\+\\\\$,\\\\\"\\\\.a-zA-Z0-9_]{0,63}\u0027\n// index.mjs \u2014 prefer a sticky regex anchored at `pos` over text.slice(pos).\n```\n\n### Affected / disclosure\nAll versions through 5.0.1 (latest); same code on `master`. cve-mcp/OSV report no known vulnerability for\nlinkify-it. Distinct from markdown-it\u0027s own `*`-run ReDoS (CVE-2026-2327, different package/path) and the\nrecent markdown-it DoS. Reported privately; happy to test a patch against the PoC.",
  "id": "GHSA-v245-v573-v5vm",
  "modified": "2026-07-21T19:06:09Z",
  "published": "2026-07-21T19:06:09Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/markdown-it/linkify-it/security/advisories/GHSA-v245-v573-v5vm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59887"
    },
    {
      "type": "WEB",
      "url": "https://github.com/markdown-it/linkify-it/commit/105e5d77f7d119871d2b2d86ed208568eb3e7ffe"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/markdown-it/linkify-it"
    },
    {
      "type": "WEB",
      "url": "https://github.com/markdown-it/linkify-it/releases/tag/5.0.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "linkify-it: Quadratic-complexity DoS via the `mailto:` validator scan-loop on attacker text"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "rack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.2.23"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "rack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0.beta1"
            },
            {
              "fixed": "3.1.21"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "rack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.2.0"
            },
            {
              "fixed": "3.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34230"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-02T20:32:19Z",
    "nvd_published_at": "2026-04-02T17:16:23Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\n`Rack::Utils.select_best_encoding` processes `Accept-Encoding` values with quadratic time complexity when the header contains many wildcard (`*`) entries. Because this method is used by `Rack::Deflater` to choose a response encoding, an unauthenticated attacker can send a single request with a crafted `Accept-Encoding` header and cause disproportionate CPU consumption on the compression middleware path.\n\nThis results in a denial of service condition for applications using `Rack::Deflater`.\n\n## Details\n\n`Rack::Utils.select_best_encoding` expands parsed `Accept-Encoding` values into a list of candidate encodings. When an entry is `*`, the method computes the set of concrete encodings by subtracting the encodings already present in the request:\n\n```ruby\nif m == \"*\"\n  (available_encodings - accept_encoding.map(\u0026:first)).each do |m2|\n    expanded_accept_encoding \u003c\u003c [m2, q, preference]\n  end\nelse\n  expanded_accept_encoding \u003c\u003c [m, q, preference]\nend\n```\n\nBecause `accept_encoding.map(\u0026:first)` is evaluated inside the loop, it is recomputed for each wildcard entry. If the request contains `N` wildcard entries, this produces repeated scans over the full parsed header and causes quadratic behavior.\n\nAfter expansion, the method also performs additional work over `expanded_accept_encoding`, including per-entry deletion, which further increases the cost for large inputs.\n\n`Rack::Deflater` invokes this method for each request when the middleware is enabled:\n\n```ruby\nUtils.select_best_encoding(ENCODINGS, Utils.parse_encodings(accept_encoding))\n```\n\nAs a result, a client can trigger this expensive code path simply by sending a large `Accept-Encoding` header containing many repeated wildcard values.\n\nFor example, a request with an approximately 8 KB `Accept-Encoding` header containing about 1,000 `*;q=0.5` entries can cause roughly 170 ms of CPU time in a single request on the `Rack::Deflater` path, compared to a negligible baseline for a normal header.\n\nThis issue is distinct from CVE-2024-26146. That issue concerned regular expression denial of service during `Accept` header parsing, whereas this issue arises later during encoding selection after the header has already been parsed.\n\n## Impact\n\nAny Rack application using `Rack::Deflater` may be affected.\n\nAn unauthenticated attacker can send requests with crafted `Accept-Encoding` headers to trigger excessive CPU usage in the encoding selection logic. Repeated requests can consume worker time disproportionately and reduce application availability.\n\nThe attack does not require invalid HTTP syntax or large payload bodies. A single header-sized request is sufficient to reach the vulnerable code path.\n\n## Mitigation\n\n* Update to a patched version of Rack in which encoding selection does not repeatedly rescan the parsed header for wildcard entries.\n* Avoid enabling `Rack::Deflater` on untrusted traffic.\n* Apply request filtering or header size / format restrictions at the reverse proxy or application boundary to limit abusive `Accept-Encoding` values.",
  "id": "GHSA-v569-hp3g-36wr",
  "modified": "2026-05-13T16:18:11Z",
  "published": "2026-04-02T20:32:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rack/rack/security/advisories/GHSA-v569-hp3g-36wr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34230"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/rack/rack"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-34230.yml"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "rack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0.beta1"
            },
            {
              "fixed": "3.1.21"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "rack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.2.0"
            },
            {
              "fixed": "3.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34827"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-407",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-02T20:30:12Z",
    "nvd_published_at": "2026-04-02T18:16:33Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\n`Rack::Multipart::Parser#handle_mime_head` parses quoted multipart parameters such as `Content-Disposition: form-data; name=\"...\"` using repeated `String#index` searches combined with `String#slice!` prefix deletion. For escape-heavy quoted values, this causes super-linear processing.\n\nAn unauthenticated attacker can send a crafted `multipart/form-data` request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing.\n\nThis results in a denial of service condition in Rack applications that accept multipart form data.\n\n## Details\n\n`Rack::Multipart::Parser#handle_mime_head` parses quoted parameter values by repeatedly:\n\n1. Searching for the next quote or backslash,\n2. Copying the preceding substring into a new buffer, and\n3. Removing the processed prefix from the original string with `slice!`.\n\nAn attacker can exploit this by sending a multipart request with many parts whose `name` parameters contain long escape-heavy values such as:\n\n```text\nname=\"a\\\\a\\\\a\\\\a\\\\a\\\\...\"\n```\n\nUnder default Rack limits, a request can contain up to 4095 parts. If many of those parts use long quoted values with dense escape characters, the parser performs disproportionately expensive CPU work while remaining within normal request size and part-count limits.\n\n## Impact\n\nAny Rack application that accepts `multipart/form-data` requests may be affected, including file upload endpoints and standard HTML form handlers.\n\nAn unauthenticated attacker can send crafted multipart requests that consume excessive CPU time during request parsing. Repeated requests can tie up application workers, reduce throughput, and degrade or deny service availability.\n\n## Mitigation\n\n* Update to a patched version of Rack that parses quoted multipart parameters without repeated rescanning and destructive prefix deletion.\n* Apply request throttling or rate limiting to multipart upload endpoints.\n* Where operationally feasible, restrict or isolate multipart parsing on untrusted high-volume endpoints.",
  "id": "GHSA-v6x5-cg8r-vv6x",
  "modified": "2026-05-13T16:18:33Z",
  "published": "2026-04-02T20:30:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34827"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/rack/rack"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-34827.yml"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Rack\u0027s multipart header parsing allows Denial of Service via escape-heavy quoted parameters"
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.4.2"
      },
      "package": {
        "ecosystem": "npm",
        "name": "decode-uri-component"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.5.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45822"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1176",
      "CWE-400",
      "CWE-405",
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-31T22:10:20Z",
    "nvd_published_at": "2026-06-30T09:16:25Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nAn attacker who can supply input to `decodeUriComponent()` (directly or via a dependency that uses this package on URL/query/path data) can cause excessive CPU usage and application unresponsiveness. This is an availability issue; there is no known memory corruption, data disclosure, or remote code execution impact.\n\n### Patches\nUpgrade to `decode-uri-component@0.5.0`.\n\n### Workarounds\nLimit the size of the input.",
  "id": "GHSA-vcc3-ghjq-m6fr",
  "modified": "2026-08-31T22:10:20Z",
  "published": "2026-08-31T22:10:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/SamVerschueren/decode-uri-component/security/advisories/GHSA-vcc3-ghjq-m6fr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45822"
    },
    {
      "type": "WEB",
      "url": "https://github.com/SamVerschueren/decode-uri-component/commit/fa479dafeede7bedf04e5c89aa78f2a78c664005"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/SamVerschueren/decode-uri-component"
    },
    {
      "type": "WEB",
      "url": "https://github.com/SamVerschueren/decode-uri-component/blob/00662938dc7c6241547ae8abce7785cc13ffd3f6/index.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/SamVerschueren/decode-uri-component/releases/tag/v0.5.0"
    },
    {
      "type": "WEB",
      "url": "https://www.npmjs.com/package/decode-uri-component"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/S:N/AU:Y/R:U/V:D/RE:M/U:Amber",
      "type": "CVSS_V4"
    }
  ],
  "summary": "decode-uri-component: Denial of service via exponential decoding of malformed percent-encoded input"
}

{
  "affected": [],
  "aliases": [
    "CVE-2026-90776"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-13T12:17:16Z",
    "severity": "HIGH"
  },
  "details": "Nodemailer versions 9.1.0 through 10.0.4 contain a quadratic time complexity vulnerability in the addressparser component when parsing email addresses with RFC 5322 comments. Attackers can craft malicious email headers with comment-separated atoms to consume excessive CPU and block the Node.js event loop for several seconds, causing denial of service.",
  "id": "GHSA-vm5r-23w9-m8hx",
  "modified": "2026-09-13T12:31:12Z",
  "published": "2026-09-13T12:31:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodemailer/nodemailer/security/advisories/GHSA-prgh-xp8r-p3m5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90776"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodemailer/nodemailer/commit/c07f17518d25aca8ab2ad66968dcbca538c24b89"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodemailer/nodemailer"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodemailer/nodemailer/blob/v10.0.4/src/addressparser/index.ts#L251"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nodemailer/nodemailer/releases/tag/v10.0.5"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nodemailer-9.1.0-through-10.0.4-denial-of-service-via-quadratic-address-parsing"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.10.2"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "nltk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-81723"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T14:34:11Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`XMLCorpusView._read_xml_fragment()` reads a corpus file in 1 KiB blocks, appending\neach block to a growing `fragment` string, then calls `_VALID_XML_RE.match(fragment)`\non the full accumulated buffer every iteration. Because each iteration rescans the\nentire accumulated fragment, the total amount of work grows quadratically with input\nsize.\n\nCommit `c9c332284` (CWE-1333) made each `match()` call linear. The quadratic behavior\nis separate: the loop calls `match()` once per 1 KiB block, each time on a longer\nbuffer.\n\nOn the test system, an 8 MiB malformed XML file consumed approximately 48 CPU-seconds\nthrough the public `BNCCorpusReader.words()` API with no source modification. Absolute\ntimings vary by hardware. `_read_xml_fragment()` imposes no limit on fragment size or\niteration count.\n\n## Details\n\n**File:** `nltk/corpus/reader/xmldocs.py`  \n**Function:** `XMLCorpusView._read_xml_fragment()`, lines 261\u2013308\n\nThe relevant loop:\n\n```python\nfragment = \"\"\nwhile True:\n    fragment += stream.read(self._BLOCK_SIZE)      # grows by 1 KiB per iteration\n    if self._VALID_XML_RE.match(fragment):         # rescans full buffer each time\n        return fragment\n    ...\n    last_open_bracket = fragment.rfind(\"\u003c\")\n    if last_open_bracket \u003e 0:                      # False for single-\u0027\u003c\u0027 payload\n        if self._VALID_XML_RE.match(fragment[:last_open_bracket]):\n            return ...\n    # loop continues\n```\n\nFor a payload of `b\u0027\u003c\u0027 + b\u0027a\u0027 * (N-1)`:\n\n- For this malformed input, `_VALID_XML_RE.match(fragment)` does not succeed because\n  the unterminated tag prevents the expression from matching before EOF.\n- `fragment.rfind(\"\u003c\")` returns `0`; the guard `last_open_bracket \u003e 0` is `False`, so\n  the backtrack branch is never taken.\n- The only exit is EOF, after all N bytes are consumed.\n\n**Affected readers** -\u003e readers that rely on `XMLCorpusView`, including\n`BNCCorpusReader`, `NPSChatCorpusReader`, `SemcorCorpusReader`, `MTECorpusReader`,\n`NKJPCorpusReader`, `FrameNetCorpusReader`, `VerbNetCorpusReader`, and direct\n`XMLCorpusView` instantiation. `XMLCorpusReader.xml()` is not affected -\u003e it calls\n`defusedxml.safe_parse()`.\n\n## PoC\n\nRequires only `pip install nltk`. No corpus data needed.\n\n```python\nfrom pathlib import Path\nfrom tempfile import TemporaryDirectory\nfrom time import perf_counter\nfrom nltk.corpus.reader.bnc import BNCCorpusReader\n\nSIZES_KIB = (256, 512, 1024, 2048, 4096, 8192)\nresults = []\nwith TemporaryDirectory() as directory:\n    root = Path(directory)\n    malformed = root / \"unterminated.xml\"\n    for kib in SIZES_KIB:\n        malformed.write_bytes(b\"\u003c\" + b\"a\" * (kib * 1024 - 1))\n        t = perf_counter()\n        try:\n            list(BNCCorpusReader(str(root), [malformed.name]).words())\n        except ValueError as e:\n            assert \"tag not closed\" in str(e)\n        results.append(perf_counter() - t)\n\nprint(\"KiB      seconds   growth\")\nfor i, (kib, elapsed) in enumerate(zip(SIZES_KIB, results)):\n    ratio = \"-\" if i == 0 else f\"{elapsed / results[i-1]:.2f}x\"\n    print(f\"{kib:5d}  {elapsed:9.3f}  {ratio}\")\n```\n\nRuntime should increase by approximately fourfold for each doubling of input size,\nalthough absolute timings vary by hardware.\n\nDuring verification, `_VALID_XML_RE.match()` was instrumented to record the size of\neach input. For a 256 KiB malformed file it was invoked 257 times on monotonically\nincreasing buffers (1024, 2048, \u2026, 262144 bytes), with the final call occurring after\nEOF. This confirms that every iteration rescans the accumulated fragment.\n\n## Impact\n\nApplications that process attacker-controlled XML corpus files through an affected reader\nare vulnerable. The attacker needs only write access to a path the reader will open. No\nNLTK credentials or special privileges required. Offline tools reading only trusted\nlocal corpora are not at risk.\n\n**Affected versions:** Verified in NLTK 3.9.4, 3.10.0, and the current develop branch.\nHistorical inspection indicates the same loop structure has existed since the\nintroduction of `XMLCorpusView` (2007), but only the listed versions were\nexperimentally verified. No patch exists in any published release.\n\nThis issue results in CPU exhaustion and may allow denial of service in applications\nthat process attacker-controlled XML corpus files.\n\n## Suggested Fix\n\nAvoid rescanning the accumulated fragment from the beginning after each 1 KiB read.\nIncremental parsing, bounded fragment accumulation, or another streaming approach would\neliminate the quadratic behavior while preserving existing semantics.\n\nA regression test should verify that `BNCCorpusReader.words()` raises `ValueError`\nwithin a fixed timeout (e.g. 5 seconds) against a 2 MiB malformed input. The existing\n`test_xmldocs_security.py` covers only the prior ReDoS payloads and does not exercise\nthis path.",
  "id": "GHSA-vp2x-qp44-57v7",
  "modified": "2026-09-02T14:34:11Z",
  "published": "2026-09-02T14:34:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/security/advisories/GHSA-vp2x-qp44-57v7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81723"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/commit/7808692d451b962711005d954859bb83aabcf8fa"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nltk/nltk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nltk/nltk/releases/tag/v3.10.3"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/nltk-before-3.10.3-quadratic-cpu-exhaustion-via-xmlcorpusview"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "Django"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.2a1"
            },
            {
              "fixed": "5.2.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "Django"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.1a1"
            },
            {
              "fixed": "5.1.15"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "Django"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.2a1"
            },
            {
              "fixed": "4.2.27"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-64460"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-03T16:59:02Z",
    "nvd_published_at": "2025-12-02T16:15:56Z",
    "severity": "MODERATE"
  },
  "details": "An issue was discovered in 5.2 before 5.2.9, 5.1 before 5.1.15, and 4.2 before 4.2.27.\nAlgorithmic complexity in `django.core.serializers.xml_serializer.getInnerText()` allows a remote attacker to cause a potential denial-of-service attack triggering CPU and memory exhaustion via specially crafted XML input processed by the XML `Deserializer`.\nEarlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected.\nDjango would like to thank Seokchan Yoon for reporting this issue.",
  "id": "GHSA-vrcr-9hj9-jcg6",
  "modified": "2026-06-05T14:34:31Z",
  "published": "2025-12-02T18:30:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-64460"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django/django/commit/0db9ea4669312f1f4973e09f4bca06ab9c1ec74b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django/django/commit/1dbd07a608e495a0c229edaaf84d58d8976313b5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django/django/commit/4d2b8803bebcdefd2b76e9e8fc528d5fddea93f0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django/django/commit/99e7d22f55497278d0bcb2e15e72ef532e62a31d"
    },
    {
      "type": "WEB",
      "url": "https://docs.djangoproject.com/en/dev/releases/security"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/django/django"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/django/PYSEC-2025-109.yaml"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/django-announce"
    },
    {
      "type": "WEB",
      "url": "https://www.djangoproject.com/weblog/2025/dec/02/security-releases"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Django is vulnerable to DoS via XML serializer text extraction"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "golang.org/x/net/html"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.45.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-47911"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-12T22:06:13Z",
    "nvd_published_at": "2026-02-05T18:16:09Z",
    "severity": "MODERATE"
  },
  "details": "The html.Parse function in golang.org/x/net/html has quadratic parsing complexity when processing certain inputs, which can lead to Denial of Service (DoS) if an attacker provides specially crafted HTML content.",
  "id": "GHSA-w4gw-w5jq-g9jh",
  "modified": "2026-02-12T22:06:13Z",
  "published": "2026-02-12T22:06:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-47911"
    },
    {
      "type": "WEB",
      "url": "https://github.com/golang/vulndb/issues/4440"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/cl/709876"
    },
    {
      "type": "PACKAGE",
      "url": "https://go.googlesource.com/net"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/golang-announce/c/jnQcOYpiR2c"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-4440"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "golang.org/x/net/html has a Quadratic Parsing Complexity issue"
}