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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63384
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-20 18:16:36 UTC
Updated2026-08-20 20:17:45 UTC
DescriptionLibevent 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.

Risk And Classification

Primary CVSS: v4.0 8.7 HIGH from [email protected]

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-190 | CWE-190 CWE-190: Integer Overflow or Wraparound

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED8.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Libevent Libevent affected >= 2.2.0-alpha, < 2.2.2-alpha Not specified
CNA Libevent Libevent affected < 2.1.13 Not specified

References

ReferenceSourceLinkTags
github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e664... [email protected] github.com
github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/libevent/libevent/releases/tag/release-2.1.13-stable [email protected] github.com
github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9... [email protected] github.com
github.com/libevent/libevent/releases/tag/release-2.2.2-alpha [email protected] github.com
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