Input validation error in resolv - CVE-2026-80213
Published: August 27, 2026
Vulnerability identifier: #VU145889
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-80213
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass hostname validation restrictions.
The vulnerability exists due to improper input validation in the resolv hostname resolution logic when resolving a hostname after it has been checked against an allow list or SSRF filter. A remote attacker can supply a crafted hostname so that the validated string and the name sent to the network differ to bypass hostname validation restrictions.
This requires a hostname that exceeds DNS length limits.
Affected software
resolv
How to mitigate CVE-2026-80213
Install security update from vendor's website.
resolv - addressed in versions 0.3.2, 0.7.2