CVE-2026-63387Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response
Updated under an hour ago ()
Does this affect you?
It affects libevent. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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.
- CVSS
- 7.0 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
- Weakness (CWE)
- CWE-121, CWE-193, CWE-787
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Awaiting Analysis
- Record last updated
- Aug 25, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
libevent libevent libevent:libevent (from the name) | from 2.2.0-alpha, < 2.2.2-alpha; before 2.1.13 | CNA record |
References
- https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47x-refsource-confirm
- https://github.com/libevent/libevent/releases/tag/release-2.1.13-stablex-refsource-misc
- https://github.com/libevent/libevent/releases/tag/release-2.2.2-alphax-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.