What’s Vulnerable › Vulnerabilities

CVE-2026-63384: Libevent: `evtag_unmarshal_header()` decodes a wire `uint32` length into a signed `int` return value.

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-26
• Weakness: CWE-190

Description

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an incorrect integer conversion in event_tagging.c when evtag_unmarshal_header uses evtag_decode_int to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INT_MAX become negative or truncated, and evtag_unmarshal_string can use the converted value in allocation sizing, producing a wrapped large allocation request and denial of service. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Affected products

• libevent: from 2.2.0-alpha, < 2.2.2-alpha; before 2.1.13

References

• https://github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e6646bda
• https://github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9c416
• https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
• https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
• https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8
• https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8

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