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CVE-2026-63387

7.0 · HIGH

Libevent is an event notification library.

Published Aug 20, 2026CWE-121EPSS 0.42%

Overview

CVE-2026-63387 is a high-severity vulnerability. It was published on August 20, 2026 and has a CVSS 3.1 base score of 7.0 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.0, 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. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 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/releases/tag/release-2.1.13-stableGitHubgithub.com/libevent/libevent/releases/tag/release-2.2.2-alphaGitHubgithub.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47GitHubgithub.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47

How CyberStrike helps

Frequently asked questions

What is CVE-2026-63387?

CVE-2026-63387 is a high-severity vulnerability. It was published on August 20, 2026 and has a CVSS 3.1 base score of 7.0 (HIGH).

How severe is CVE-2026-63387?

This vulnerability has a CVSS 3.1 base score of 7.0, 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-2026-63387?

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-2026-63387?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-63387 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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