Stack-based buffer overflow in libevent - #VU136940
Published: July 6, 2026
Vulnerability identifier: #VU136940
CSH Severity: Medium
CVSS v4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service or corrupt adjacent stack state.
The vulnerability exists due to stack-based buffer overflow in dnsname_to_labels() in evdns.c when formatting DNS server responses containing name-bearing records. A remote attacker can send a specially crafted DNS query that causes the application to generate a crafted response to cause a denial of service or corrupt adjacent stack state.
The issue is triggered by an off-by-one condition when name encoding reaches the exact end of a 64 KB stack buffer before a terminating null byte is appended.
Affected software
libevent
Remediation
Install security update from vendor's website.
libevent - update to 2.1.13