CVE-2026-63384: libevent Integer Overflow or Wraparound

Vulnerability summary

CVE-2026-63384 is a high (CVSS 8.7) Integer Overflow or Wraparound vulnerability in libevent. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 43.2% of scored vulnerabilities.

Timeline

1. 20-08-2026
   PublishedVulnerability first disclosed.
2. 20-08-2026
   Last modifiedVulnerability information updated.

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.

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.