Input validation error in Dnsmasq - CVE-2026-4890
Published: May 12, 2026
Vulnerability identifier: #VU131140
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-4890
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 cause a denial of service.
The vulnerability exists due to improper input validation in NSEC bitmap parsing in dnssec.c when processing crafted DNSSEC NSEC or NSEC3 records. A remote attacker can send a specially crafted DNS response to cause a denial of service.
No valid DNSSEC signatures are needed because the issue is reachable before RRSIG validation.
How to mitigate CVE-2026-4890
Install security update from vendor's website.