Use After Free Affecting unbound-debuginfo package, versions <0:1.17.1-1.amzn2023.0.15


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.38% (30th percentile)

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  • Snyk IDSNYK-AMZN2023-UNBOUNDDEBUGINFO-20246940
  • published29 Sept 2026
  • disclosed16 Sept 2026

Introduced: 16 Sep 2026

CVE-2026-82720  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 unbound-debuginfo to version 0:1.17.1-1.amzn2023.0.15 or higher.
This issue was patched in ALAS2023-2026-3127.

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 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'. During failure code paths (i.e., RPZ drop query, jostle due to heavy traffic), a dropped DoH stream brings down the whole DoH session and does not account properly for other DoH streams in the same session. This leads to use-after-free in those code paths. If the prerequisites are satisfied (possible RPZ drop or heavy client traffic), a malicious actor can trigger the vulnerability with a single DoH connection and the appropriate traffic. Impact is limited as the reads are not user controlled and the use-after-free leads to early returns. However, a hardened allocator can catch the use-after-free and controllably terminate the process resulting to denial of service.

CVSS Base Scores

version 3.1