CVE-2026-52863

NameCVE-2026-52863
DescriptionIn NLnet Labs Unbound 1.25.0 up to and including 1.25.1, a fix that makes the 'respip' and 'dns64' modules work together, creates a shallow copy of the view name in effect that could lead to memory corruption if the owner of the original view name is jostled out when Unbound is under pressure. Unbound needs to be configured with one of 'respip'/'rpz' modules, together with a module that can attach subqueries (respip CNAME redirection, dns64, subnetcache) and a configured 'access-control-view' while Unbound is under pressure so that joslte logic kicks in and starts dropping slow queries. The subquery is getting a shallow copy of the view name and if the super query which owns the view name is jostled out, memory corruption can occur. Likelihood of a crash is low, since it relies heavily on the underlying memory allocator and the memory layout. Debug memory builds (e.g., ASAN) that catch the free terminate the server.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
unbound (PTS)bullseye1.13.1-1+deb11u2vulnerable
bullseye (security)1.13.1-1+deb11u7vulnerable
bookworm1.17.1-2+deb12u4vulnerable
bookworm (security)1.17.1-2+deb12u3vulnerable
trixie (security), trixie1.22.0-2+deb13u3vulnerable
forky, sid1.26.0-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
unboundsource(unstable)1.25.2-1

Notes

https://community.nlnetlabs.nl/t/unbound-1-25-2-released/3430

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