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CVE-2026-82720 on Cyberus Linux 26.05

Aliases: CVE-2026-82720

Packages: unbound

Status: In Progress

Advisory Information

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.

Updates

2026-09-22 11:14 CEST

Metadata changes:

  • Status for package unbound: “In Progress”

2026-09-22 11:07 CEST

Metadata changes:

  • Status for package unbound: “New”