Time-of-check Time-of-use (TOCTOU) Affecting unbound-debuginfo package, versions <0:1.17.1-1.amzn2023.0.12


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.05% (17th percentile)

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  • Snyk IDSNYK-AMZN2023-UNBOUNDDEBUGINFO-16887610
  • published27 May 2026
  • disclosed20 May 2026

Introduced: 20 May 2026

NewCVE-2026-44608  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 unbound-debuginfo to version 0:1.17.1-1.amzn2023.0.12 or higher.
This issue was patched in ALAS2023-2026-1756.

NVD Description

Note: Versions mentioned in the description apply only to the upstream unbound-debuginfo package and not the unbound-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1