dnsdist: An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being fr...
CVE-2026-40211 is fixed in dnsdist on 1 platform, first by DEBIAN-CVE-2026-40211, released June 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| dnsdist · Debian 13.5 (trixie) | 1.9.15-0+deb13u1 | DEBIAN-CVE-2026-40211 | Jun 26, 2026 |
| dnsdist · Debian 14 | 2.1.0-1 | DEBIAN-CVE-2026-40211 | Jun 26, 2026 |
| dnsdist · opensuse-leap 16.0 | 1.9.15-160000.1.1 | OPENSUSE-SU-2026:21533-1 | Aug 5, 2026 |
| dnsdist · sles 16.0 | 1.9.15-160000.1.1 | SUSE-SU-2026:23146-1 | Aug 5, 2026 |
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