CVE-2026-63387
7.0
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Exploitability: 2.2 / Impact: 4.7
Source: security-advisories@github.com (Secondary)
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.
Related CWEs
CWE-121
Stack-based Buffer Overflow
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CWE-193
Off-by-one Error
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
CWE-787
Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
References (4)
Source: security-advisories@github.com
Source: security-advisories@github.com
Source: security-advisories@github.com
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Timeline
No history available yet.