ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-44608

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR re…

Published May 20, 2026 · catalog updated Jul 24, 2026 · OpenBSD OpenBSD

Check if you run it

No confirmed exploitation is on record for CVE-2026-44608. EPSS is 0.28%. Act only if a listed version of OpenBSD OpenBSD is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium4.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.28%
Remediation
Vendor / distro source
Affected products
cpe nlnetlabs/unbound

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe nlnetlabs/unboundversion unspecified

How to fix CVE-2026-44608

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-44608. EPSS is 0.28%. Act only if a listed version of OpenBSD OpenBSD is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-413. EPSS 0.28%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 20, 2026 · NIST NVD

    Detected

    NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, a

  2. Jul 24, 2026 · NIST NVD

    Updated

    NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, a

Sources

  • CVE.orgVulnerability recordCVE-2026-44608

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-44608

    30-day exploitation probability 0.3%

    first.org
  • FreeBSD SecurityVendor advisoryCVE-2026-44608

    CVE-2026-44608 is named by FreeBSD Security.

    freebsd.org
  • NIST NVDVulnerability recordCVE-2026-44608

    NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with 'rpz-nsip'/'rpz-nsdname' triggers) it could result in heap use-after-free and eventual crash.

    nvd.nist.gov
  • OpenBSD ErrataVendor advisoryCVE-2026-44608

    CVE-2026-44608 is named on the public OpenBSD Errata page.

    openbsd.org

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

CVE-2026-44608: OpenBSD OpenBSD — NLnet Labs Unbound 1.14.0 up to a… · ZeroDay Findings