Incorrect Control Flow Scoping in dnsdist - CVE-2026-40208
Published: June 25, 2026
Vulnerability identifier: #VU135338
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-40208
CWE-ID: CWE-705
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 incorrect handling of invalid frames in the DoH3 query processing logic when processing DoH3 GET queries with an invalid DATA frame. A remote attacker can send crafted DoH3 GET queries with an invalid DATA frame to cause a denial of service.
The issue can delay the processing of DoH3 queries.
Affected software
dnsdist
Debian Linux
dnsdist (Debian package)
Debian Linux
dnsdist (Debian package)
How to mitigate CVE-2026-40208
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