| Name | CVE-2026-40209 |
| Description | 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DSA-6367-1 |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| dnsdist (PTS) | bullseye | 1.5.1-3 | vulnerable |
| bookworm | 1.7.3-2 | vulnerable |
| trixie | 1.9.14-0+deb13u1 | vulnerable |
| trixie (security) | 1.9.15-0+deb13u1 | fixed |
| forky | 2.0.5-2 | vulnerable |
| sid | 2.0.6-1 | vulnerable |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| dnsdist | source | bullseye | (unfixed) | end-of-life |
| dnsdist | source | bookworm | (unfixed) | end-of-life |
| dnsdist | source | trixie | 1.9.15-0+deb13u1 | DSA-6367-1 |
| dnsdist | source | (unstable) | (unfixed) |
Notes
[bookworm] - dnsdist <end-of-life> (See #1119290)
[bullseye] - dnsdist <end-of-life> (see #1119290)
https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-09.html#cve-2026-40209-denial-of-service-via-ixfr-queries
