CVE-2026-82720
mediumpriority · track · 0EPSS 0.004 · 32 %ileDEUSEPSS · scored 2026-10-27
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (14)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3392Unbound: Mehrere SchwachstellenDeutsch2026-09-15csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Unbound ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Speicher zu korrumpieren, einen Denial of Service zu verursachen oder Code auszuführen.
sources
Which sources assert this record, and when.
references (1) nvd
External citations — patches, advisories, analysis.
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-82720.txtPatchVendor Advisory
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