Stack-based Buffer Overflow Affecting libevent package, versions <2.1.12-stable-10+e1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.42% (34th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LIBEVENT-19166027
  • published22 Aug 2026
  • disclosed20 Aug 2026

Introduced: 20 Aug 2026

CVE-2026-63387  (opens in a new tab)
CWE-121  (opens in a new tab)
CWE-193  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Echo:latest libevent to version 2.1.12-stable-10+e1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libevent package and not the libevent package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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 Base Scores

version 3.1