dnsdist: An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of...
CVE-2026-40209 is fixed in dnsdist on 1 platform, first by DEBIAN-CVE-2026-40209, released June 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.
An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| dnsdist · Debian 13.5 (trixie) | 1.9.15-0+deb13u1 | DEBIAN-CVE-2026-40209 | Jun 26, 2026 |
| dnsdist · Debian 14 | 2.1.0-1 | DEBIAN-CVE-2026-40209 | 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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