CVE-2026-63379 (GCVE-0-2026-63379)
Vulnerability from cvelistv5
Published
2026-08-20 17:55
Modified
2026-08-25 15:14
Severity ?
6.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Summary
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
References
Impacted products
Vendor Product Version
libevent libevent Version: < 2.1.13
Version: >= 2.2.0-alpha, < 2.2.2-alpha
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-63379",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-25T15:14:11.010475Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-25T15:14:26.228Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "libevent",
          "vendor": "libevent",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.1.13"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req-\u003einput_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T17:55:00.789Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485"
        },
        {
          "name": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"
        },
        {
          "name": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"
        }
      ],
      "source": {
        "advisory": "GHSA-2gmv-p5m7-98p6",
        "discovery": "UNKNOWN"
      },
      "title": "Libevent: HTTP Header smuggling"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63379",
    "datePublished": "2026-08-20T17:55:00.789Z",
    "dateReserved": "2026-07-16T17:39:30.170Z",
    "dateUpdated": "2026-08-25T15:14:26.228Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-63379\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-25T15:14:11.010475Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-25T15:14:22.389Z\"}}], \"cna\": {\"title\": \"Libevent: HTTP Header smuggling\", \"source\": {\"advisory\": \"GHSA-2gmv-p5m7-98p6\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 6.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"LOW\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"LOW\"}}], \"affected\": [{\"vendor\": \"libevent\", \"product\": \"libevent\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 2.1.13\"}, {\"status\": \"affected\", \"version\": \"\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha\"}]}], \"references\": [{\"url\": \"https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6\", \"name\": \"https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636\", \"name\": \"https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485\", \"name\": \"https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\", \"name\": \"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\", \"name\": \"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req-\u003einput_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.\"}], \"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\": \"2026-08-20T17:55:00.789Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-63379\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-25T15:14:26.228Z\", \"dateReserved\": \"2026-07-16T17:39:30.170Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-08-20T17:55:00.789Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.