CVE-2026-12725

A heap-based buffer overflow was found in dnsmasq. When DNSSEC validation and query logging are both enabled, logging of DS or DNSKEY replies containing unsupported algorithm or digest types can cause dnsmasq to write past the end of an internal logging buffer. A remote attacker able to supply such a DNS response may crash the dnsmasq process, resulting in denial of service.

Red Hat Product Security rates this issue as Moderate. The overflow occurs in the query logging path only, requires both DNSSEC validation and query logging to be enabled, involves a bounded overwrite with non-attacker-controlled data, and is most appropriately characterized as a denial of service rather than a confidentiality, integrity, or code execution issue. This assessment is consistent with the upstream maintainer's analysis.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigate this issue by updating to a version of dnsmasq that includes the upstream fix (commit 36d081e37477027fd721fea498f3760f529034ad), or by disabling query logging if DNSSEC validation must remain enabled. After changing the configuration, restart the dnsmasq service for the changes to take effect.