CVE-2026-82720Use-after-free in DoH stream cleanup code path
Updated under an hour ago ()
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It affects NLnet Labs Unbound and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
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
- 5.9 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-416
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- NLnet Labs
- NVD analysis
- Analyzed
- Record last updated
- Sep 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
NLnet Labs Unbound nlnet_labs:unbound (from the name) | from 1.12.0 before 1.26.1 | CNA record |
nlnetlabs unbound nlnetlabs:unbound | from 1.12.0 before 1.26.1 | NVD |
References
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-82720.txtvendor-advisory, patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.