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CVE-2026-63495

7.5 · HIGH

Libevent is an event notification library.

Published Aug 20, 2026CWE-400EPSS 0.61%

Overview

CVE-2026-63495 is a high-severity vulnerability. It was published on August 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077bGitHubgithub.com/libevent/libevent/releases/tag/release-2.2.2-alphaGitHubgithub.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmxGitHubgithub.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx

How CyberStrike helps

Frequently asked questions

What is CVE-2026-63495?

CVE-2026-63495 is a high-severity vulnerability. It was published on August 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-63495?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-63495?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-63495?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-63495 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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