CVE-2026-63495

Summary

Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha.

Affected Software

Weaknesses

• CWE-400: CWE-400: Uncontrolled Resource Consumption
• CWE-770: CWE-770: Allocation of Resources Without Limits or Throttling

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: partial

Additional References

• https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx

References

• https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx
• https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b
• https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha

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