CVE-2026-63381 (GCVE-0-2026-63381)
Vulnerability from cvelistv5
Published
2026-08-20 17:50
Modified
2026-08-21 21:46
Severity ?
5.8 (Medium) - CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
CWE
  • CWE-908 - Use of Uninitialized Resource
Summary
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
References
Impacted products
Vendor Product Version
libevent libevent Version: >= 2.2.0-alpha, < 2.2.2-alpha
Version: < 2.1.13
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            "other": {
              "content": {
                "id": "CVE-2026-63381",
                "options": [
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                    "Exploitation": "none"
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                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-21T20:58:46.599802Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-08-21T21:46:33.792Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
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          "vendor": "libevent",
          "versions": [
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              "version": "\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha"
            },
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              "version": "\u003c 2.1.13"
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      "descriptions": [
        {
          "lang": "en",
          "value": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf-\u003efirst, outbuf-\u003elast, or outbuf-\u003elast_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 5.8,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW"
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          "descriptions": [
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              "description": "CWE-908: Use of Uninitialized Resource",
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              "type": "CWE"
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      "providerMetadata": {
        "dateUpdated": "2026-08-20T17:50:09.322Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
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      "references": [
        {
          "name": "https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-cg4r-88c8",
          "tags": [
            "x_refsource_CONFIRM"
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          "url": "https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-cg4r-88c8"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9",
          "tags": [
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          "url": "https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9"
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        {
          "name": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable",
          "tags": [
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          "url": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"
        },
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          "name": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
          "tags": [
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          "url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"
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      "source": {
        "advisory": "GHSA-c2pj-cg4r-88c8",
        "discovery": "UNKNOWN"
      },
      "title": "Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`"
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  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63381",
    "datePublished": "2026-08-20T17:50:09.322Z",
    "dateReserved": "2026-07-16T17:39:30.171Z",
    "dateUpdated": "2026-08-21T21:46:33.792Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}


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