CVE-2026-12505

NameCVE-2026-12505
DescriptionA flaw was found in the cifs-utils package where the cifs.upcall helper fails to securely drop its root privileges before looking up user information inside a user-controlled environment. A local, low privileged attacker can exploit this by using a crafted request_key payload to trick the root-owned helper into entering a custom environment (namespace) containing a malicious NSS module. This forces the system to load the attacker's controlled NSS Module and configuration, allowing them to execute arbitrary commands as the root user, elevating their privileges and fully compromising the system.
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
cifs-utils (PTS)bullseye2:6.11-3.1+deb11u2vulnerable
bullseye (security)2:6.11-3.1+deb11u1vulnerable
bookworm2:7.0-2vulnerable
forky, sid, trixie2:7.4-1vulnerable

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
cifs-utilssource(unstable)(unfixed)

Notes

https://bugzilla.redhat.com/show_bug.cgi?id=2489805
https://git.samba.org/?p=cifs-utils.git;a=commit;h=972c5b5ff95e3e812bc8daa72d0383654ab0dba7

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