Input validation error in dnsdist - CVE-2026-33597
Published: April 23, 2026
Vulnerability identifier: #VU126949
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-2026-33597
CWE-ID: CWE-20
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 improper input validation in the PRSD detection algorithm when processing a crafted query containing an invalid DNS label. A remote attacker can send a crafted query to cause a denial of service.
Exploitation affects PRSD detection executed via DynBlockRulesGroup:setSuffixMatchRule or DynBlockRulesGroup:setSuffixMatchRuleFFI.
Affected software
dnsdist
Debian Linux
Fedora
dnsdist (Debian package)
dnsdist
Debian Linux
Fedora
dnsdist (Debian package)
dnsdist
How to mitigate CVE-2026-33597
Install security update from vendor's website.
dnsdist - addressed in versions 1.9.13, 2.0.4
dnsdist (Debian package) - update to 1.9.14-0+deb13u1
dnsdist - update to 2.0.6-1.el10_2
dnsdist (Debian package) - update to 1.9.14-0+deb13u1
dnsdist - update to 2.0.6-1.el10_2