VDB
CVE-2026-63387
CVE-2026-63387
PUBLISHED
CVSS 7 HIGH
Reported by GitHub_M · Published August 20, 2026
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.
Risk Scores
CVSS 3.1
7
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| libevent | libevent | >= 2.2.0-alpha, < 2.2.2-alpha, < 2.1.13 |
| libevent | libevent | >= 2.2.0-alpha, < 2.2.2-alpha, < 2.1.13, >= 2.2.0-alpha, < 2.2.2-alpha |
Timeline
- Aug 20, 2026 CVE Published
- Aug 22, 2026 Coalition ESS Score
- Aug 24, 2026 EPSS Score
- Aug 26, 2026 EPSS Score
- Aug 30, 2026 EPSS Score
- Sep 3, 2026 Security Advisory
- Sep 4, 2026 EPSS Score
- Sep 9, 2026 EPSS Score
- Sep 9, 2026 CVE Updated
- Sep 10, 2026 EPSS Score
- Sep 12, 2026 EPSS Score
- Sep 16, 2026 EPSS Score
References
- https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47 x_refsource_CONFIRM
- https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable x_refsource_MISC
- https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha x_refsource_MISC