High [CVE-2026-12245] Denial of DNS over TLS service by any DoT client
This high-severity Red Hat Linux advisory covers CVE-2026-12245.
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Summary
NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing a crash of the server process, which can be triggered trivially by sending a DNS query over a DoT connection, and closing the connection without reading the response. A flaw was found in NSD.
When NSD is configured with DNS over TLS (DoT), a remote attacker can exploit a vulnerability by performing a TLS action and then prematurely closing the connection. This action causes the server process to crash and restart.
By repeatedly exploiting this flaw, an attacker can keep the server in a continuous crash-restart loop, leading to a denial of service for DoT clients. This impact is significant for environments relying on DoT for secure DNS resolution.
This vulnerability doesn't affect any supported Red Hat Product. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-617.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 21 days 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 · medium-confidence parse· fetched 21 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 21 days ago·verify at source
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