Input validation error in Dnsmasq - CVE-2026-4893
Published: May 12, 2026
Vulnerability identifier: #VU131142
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-4893
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: GNU
Affected software:
Dnsmasq
Dnsmasq
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass client subnet source validation.
The vulnerability exists due to improper input validation in check_source() handling in process_reply() when processing DNS replies with the --add-subnet feature enabled. A remote attacker can send a specially crafted DNS reply to bypass client subnet source validation.
Only configurations with --add-subnet enabled are vulnerable.
How to mitigate CVE-2026-4893
Install security update from vendor's website.