Memory leak in PowerDNS Recursor - CVE-2026-85558
Published: October 21, 2026
Vulnerability identifier: #VU156689
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-2026-85558
CWE-ID: CWE-401
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to consume memory without bounds and degrade the availability of PowerDNS Recursor.
The vulnerability exists due to a memory leak in incoming TCP client address tracking when connections close without their stored client addresses being cleaned up. A remote attacker can repeatedly establish and close incoming TCP connections to accumulate retained address data and cause excessive memory consumption.
Affected software
PowerDNS Recursor
How to mitigate CVE-2026-85558
Install security update from vendor's website.
PowerDNS Recursor - addressed in versions 5.3.12, 5.4.8