CVE-2026-82720 (GCVE-0-2026-82720)

Vulnerability from cvelistv5 – Published: 2026-09-16 08:32 – Updated: 2026-09-16 14:14
VLAI
Title
Use-after-free in DoH stream cleanup code path
Summary
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.
Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-16 14:13 UTC
CWE
Assigner
NLnet Labs CNA
CNA scorecard B 82/100 over 73 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
NLnet Labs Unbound Affected: 1.12.0 , < 1.26.1 (semver)
guessed Create a notification for this product.
Date Public
2026-09-16 00:00
Credits
Yuqi Qiu (Nankai University, AOSP Lab) Xiang Li (Nankai University, AOSP Lab)
Show details on NVD website
To clipboard 

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