Time-of-check Time-of-use (TOCTOU) Affecting rust-zbus-polkit package, versions <5.1.0-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-RUSTZBUSPOLKIT-19453042
- published1 Sept 2026
- disclosed31 Aug 2026
Introduced: 31 Aug 2026
CVE-2026-78422 (opens in a new tab)How to fix?
Upgrade Debian:unstable rust-zbus-polkit to version 5.1.0-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream rust-zbus-polkit package and not the rust-zbus-polkit package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
Subject::new_for_owner() in the zbus_polkit crate encodes the uid entry of a unix-process polkit subject as an unsigned 32-bit integer (D-Bus type u), whereas the org.freedesktop.PolicyKit1.Authority interface specifies a signed 32-bit integer (D-Bus type i). Because of this type mismatch, polkit silently discards the caller-supplied UID and instead determines the subject's owner itself by looking up the PID in /proc, a lookup that is inherently subject to a time-of-check/time-of-use race.
Consequently, an application that passes a UID obtained from a trustworthy source — for example SO_PEERCRED Unix socket peer credentials — in order to defend against PID reuse receives no protection, and the supplied UID has no effect on the authorization decision. A local unprivileged attacker who can cause an authorized process to terminate and then win the race to have their own process assigned the same PID can be authorized under the identity of the terminated process, bypassing the polkit authorization check and performing actions the attacker is not entitled to.
This issue affects zbus_polkit before 5.1.0.