CVE-2021-26910

NameCVE-2021-26910
DescriptionFirejail before 0.9.64.4 allows attackers to bypass intended access restrictions because there is a TOCTOU race condition between a stat operation and an OverlayFS mount operation.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-2554-1, DSA-4849-1
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
firejail (PTS)stretch0.9.44.8-2vulnerable
stretch (security)0.9.44.8-2+deb9u2fixed
buster0.9.58.2-2+deb10u1vulnerable
buster (security)0.9.58.2-2+deb10u2fixed
bullseye, sid0.9.64.4-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
firejailsourcestretch0.9.44.8-2+deb9u2DLA-2554-1
firejailsourcebuster0.9.58.2-2+deb10u2DSA-4849-1
firejailsource(unstable)0.9.64.4-1

Notes

https://www.openwall.com/lists/oss-security/2021/02/08/5
Fix (disabled overlayfs): https://github.com/netblue30/firejail/commit/97d8a03cad19501f017587cc4e47d8418273834b
https://unparalleled.eu/publications/2021/advisory-unpar-2021-0.txt
https://unparalleled.eu/blog/2021/20210208-rigged-race-against-firejail-for-local-root/

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