Descriptionrunuser in util-linux allows local users to escape to the parent session via a crafted TIOCSTI ioctl call, which pushes characters to the terminal's input buffer.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs815922

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
util-linux (PTS)buster2.33.1-0.1fixed
bullseye (security), bullseye2.36.1-8+deb11u1fixed
trixie, sid2.39.2-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
util-linuxsourcesqueeze(not affected)
util-linuxsourcewheezy(not affected)


[stretch] - util-linux <no-dsa> (Minor issue)
[jessie] - util-linux <no-dsa> (Minor issue)
[wheezy] - util-linux <not-affected> (runuser[.c] not yet present)
[squeeze] - util-linux <not-affected> (runuser[.c] not yet present)
Restricting ioctl on the kernel side seems the better approach, patches have been posted to kernel-hardening list
2.31 introduces a new --pty option to separate privileged and unprivileged
shells (not enabled by default and the cli switch is necessary).

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