CVE-2026-50020 (GCVE-0-2026-50020)

Vulnerability from cvelistv5 – Published: 2026-06-12 14:55 – Updated: 2026-06-12 15:56
VLAI
Title
Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted
Summary
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
Impacted products
Vendor Product Version
netty netty Affected: >= 4.2.0.Final, < 4.2.15.Final
Affected: < 4.1.135.Final
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-50020",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-12T15:56:10.783796Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-12T15:56:43.051Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "netty",
          "vendor": "netty",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.2.0.Final, \u003c 4.2.15.Final"
            },
            {
              "status": "affected",
              "version": "\u003c 4.1.135.Final"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00\u20130x1F and 0x7F) as well as all whitespace. RFC 9112 \u00a72.2 only asks servers to ignore empty CRLF lines preceding the request-line \u2014 a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-12T14:55:32.165Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c"
        },
        {
          "name": "https://github.com/netty/netty/releases/tag/netty-4.1.135.Final",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"
        },
        {
          "name": "https://github.com/netty/netty/releases/tag/netty-4.2.15.Final",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"
        }
      ],
      "source": {
        "advisory": "GHSA-hvcg-qmg6-jm4c",
        "discovery": "UNKNOWN"
      },
      "title": "Netty\u0027s HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-50020",
    "datePublished": "2026-06-12T14:55:32.165Z",
    "dateReserved": "2026-06-02T22:46:02.579Z",
    "dateUpdated": "2026-06-12T15:56:43.051Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-50020",
      "date": "2026-08-08",
      "epss": "0.00232",
      "percentile": "0.1411"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-50020\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-06-12T16:16:31.447\",\"lastModified\":\"2026-06-17T10:57:35.237\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00\u20130x1F and 0x7F) as well as all whitespace. RFC 9112 \u00a72.2 only asks servers to ignore empty CRLF lines preceding the request-line \u2014 a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"netty\",\"product\":\"netty\",\"versions\":[{\"version\":\"\u003e= 4.2.0.Final, \u003c 4.2.15.Final\",\"status\":\"affected\"},{\"version\":\"\u003c 4.1.135.Final\",\"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:N/I:L/A:N\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-06-12T15:56:10.783796Z\",\"id\":\"CVE-2026-50020\",\"options\":[{\"exploitation\":\"poc\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-444\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"4.1.135\",\"matchCriteriaId\":\"3097D962-A32D-4467-AAE7-F4CBA3A349D2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.2.0\",\"versionEndExcluding\":\"4.2.15\",\"matchCriteriaId\":\"413D4611-A46C-4BE4-AB2F-D86282F65984\"}]}]}],\"references\":[{\"url\":\"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"tags\":[\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-04T21:23:12+00:00",
      "cve": "CVE-2026-50020",
      "id": "CVE-2026-50020",
      "initial_release_date": "2026-06-12T14:55:32.165000+00:00",
      "product_status:fixed": "3",
      "product_status:known_affected": "45",
      "product_status:known_not_affected": "9",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "netty-codec-http: Netty: Data manipulation via request-boundary confusion in HttpObjectDecoder",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50020.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-50020\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-06-12T15:56:10.783796Z\"}}}], \"references\": [{\"url\": \"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-06-12T15:55:54.681Z\"}}], \"cna\": {\"title\": \"Netty\u0027s HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted\", \"source\": {\"advisory\": \"GHSA-hvcg-qmg6-jm4c\", \"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:N/I:L/A:N\", \"integrityImpact\": \"LOW\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"netty\", \"product\": \"netty\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 4.2.0.Final, \u003c 4.2.15.Final\"}, {\"status\": \"affected\", \"version\": \"\u003c 4.1.135.Final\"}]}], \"references\": [{\"url\": \"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c\", \"name\": \"https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final\", \"name\": \"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final\", \"name\": \"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00\\u20130x1F and 0x7F) as well as all whitespace. RFC 9112 \\u00a72.2 only asks servers to ignore empty CRLF lines preceding the request-line \\u2014 a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-444\", \"description\": \"CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-06-12T14:55:32.165Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-50020\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-06-12T15:56:43.051Z\", \"dateReserved\": \"2026-06-02T22:46:02.579Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-06-12T14:55:32.165Z\", \"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.