Medium [CVE-2026-12725] Dnsmasq: dnsmasq: heap buffer overflow in log_query when logging unsupported ds/dnskey replies
This medium-severity Red Hat Linux advisory covers CVE-2026-12725 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
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. Red Hat severity: Moderate — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-122. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4.
Red Hat lists Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7 as not affected. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: dnsmasq.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 48 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 48 minutes ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 48 minutes ago·verify at source
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