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CVE-2026-63387 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:7 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47	CISA-ADP
https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable	[email protected]
https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha	[email protected]
https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-121	Stack-based Buffer Overflow	[email protected]
CWE-193	Off-by-one Error	[email protected]
CWE-787	Out-of-bounds Write	[email protected]

Affected Products

No affected product data is available for this CVE.

Change History

2 change records found show changes

Date	Action	Recorded By
Aug 25, 2026	CVE Modified	CISA-ADP
Aug 20, 2026	New CVE Received	[email protected]