Allocation of Resources Without Limits or Throttling in dnsdist - CVE-2026-40211
Published: June 25, 2026
Vulnerability identifier: #VU135341
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-40211
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to allocation of resources without limits or throttling in DoH3 stream handling when processing crafted DNS over HTTP/3 queries that trigger an exception. A remote attacker can send crafted DNS over HTTP/3 queries to cause a denial of service.
The affected buffer is freed only at the end of the QUIC connection, and some setups may allow enough concurrent DoH3 streams to trigger an out-of-memory condition.
Affected software
dnsdist
Debian Linux
dnsdist (Debian package)
Debian Linux
dnsdist (Debian package)
How to mitigate CVE-2026-40211
Install security update from vendor's website.
dnsdist - addressed in versions 1.9.15, 2.0.7
dnsdist (Debian package) - update to 1.9.15-0+deb13u1
dnsdist (Debian package) - update to 1.9.15-0+deb13u1