CVE-2026-49854 (GCVE-0-2026-49854)

Vulnerability from cvelistv5 – Published: 2026-07-14 20:43 – Updated: 2026-07-15 13:26
VLAI
Title
Tornado: Out-of-bounds memory access in C extension
Summary
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
tornadoweb tornado Affected: < 6.5.6
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-49854",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-15T13:23:13.452445Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-15T13:26:39.749Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "tornado",
          "vendor": "tornadoweb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.5.6"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-126",
              "description": "CWE-126: Buffer Over-read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-14T20:43:03.977Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9"
        },
        {
          "name": "https://github.com/tornadoweb/tornado/pull/3626",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/tornadoweb/tornado/pull/3626"
        },
        {
          "name": "https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac"
        },
        {
          "name": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.6"
        }
      ],
      "source": {
        "advisory": "GHSA-cx3h-4qpv-8hc9",
        "discovery": "UNKNOWN"
      },
      "title": "Tornado: Out-of-bounds memory access in C extension"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-49854",
    "datePublished": "2026-07-14T20:43:03.977Z",
    "dateReserved": "2026-06-01T22:03:19.640Z",
    "dateUpdated": "2026-07-15T13:26:39.749Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-49854",
      "date": "2026-07-15",
      "epss": "0.0045",
      "percentile": "0.36328"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-49854\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-14T21:17:02.300\",\"lastModified\":\"2026-07-15T19:50:11.367\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"tornadoweb\",\"product\":\"tornado\",\"versions\":[{\"version\":\"\u003c 6.5.6\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-07-15T13:23:13.452445Z\",\"id\":\"CVE-2026-49854\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-126\"}]}],\"references\":[{\"url\":\"https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/tornadoweb/tornado/pull/3626\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/tornadoweb/tornado/releases/tag/v6.5.6\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9\",\"source\":\"security-advisories@github.com\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-49854\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-07-15T13:23:13.452445Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-07-15T13:23:14.145Z\"}}], \"cna\": {\"title\": \"Tornado: Out-of-bounds memory access in C extension\", \"source\": {\"advisory\": \"GHSA-cx3h-4qpv-8hc9\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"LOW\"}}], \"affected\": [{\"vendor\": \"tornadoweb\", \"product\": \"tornado\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 6.5.6\"}]}], \"references\": [{\"url\": \"https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9\", \"name\": \"https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/tornadoweb/tornado/pull/3626\", \"name\": \"https://github.com/tornadoweb/tornado/pull/3626\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac\", \"name\": \"https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/tornadoweb/tornado/releases/tag/v6.5.6\", \"name\": \"https://github.com/tornadoweb/tornado/releases/tag/v6.5.6\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-126\", \"description\": \"CWE-126: Buffer Over-read\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-07-14T20:43:03.977Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-49854\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-15T13:26:39.749Z\", \"dateReserved\": \"2026-06-01T22:03:19.640Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-07-14T20:43:03.977Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.