Vulnocalypse
Back to feed
34impact

Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response

libevent · CVE-2026-63387
0 news outlets0 CERTs and agencies0 researchers

What is it?

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.

Evidence

No coverage recorded yet.

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
7.0
EPSS
0.4%
First seen
7 d ago
Status
corroborated

All libevent vulnerabilities