Use-after-free in Unbound - CVE-2026-44608
Published: May 20, 2026
Vulnerability identifier: #VU131923
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-44608
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: NLnet Labs
Affected software:
Unbound
Unbound
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to use-after-free in RPZ zone handling when processing an RPZ XFR reload concurrently with reads of an RPZ zone using 'rpz-nsip' or 'rpz-nsdname' triggers. A remote attacker can trigger a crafted zone transfer timing condition to cause a denial of service.
Only multi-threaded deployments are affected, and local RPZ files do not trigger the vulnerability.
How to mitigate CVE-2026-44608
Install security update from vendor's website.