Systemd: systemd-tmpfiles symlink-redirected arbitrary file overwrite via a chase_safe root-to-unprivileged ownership transition bypass
Summary
A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The highest threat from this vulnerability is to integrity. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; and 2 more. Affected products named by the advisory: Red Hat Hardened Images; Red Hat OpenShift Container Platform 4.
What this means
In plain English
A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The official description requires local access to the affected system.
Recommended action
The parsed official advisory does not currently specify a fixed release, mitigation, or workaround. Review the linked vendor advisory for the latest guidance before making changes.
Rewritten locally from the scraped official advisory data above; no generative API is used. The vendor advisory is authoritative.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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