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 Details
- CVSS 3.1 Base Score: 7
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade libevent | Sep 21, 2026 | Aug 20, 2026 |
| Redhat_linux | — | Upgrade libevent-docUpgrade libevent-debuginfoUpgrade libevent-debugsourceUpgrade libeventUpgrade libevent-develNo solution exists | Aug 31, 2026 | Aug 20, 2026 |
| Rocky_linux | — | Upgrade libeventUpgrade libevent-debuginfoUpgrade libevent-debugsourceUpgrade libevent-devel | Sep 18, 2026 | Sep 17, 2026 |
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