Vulnerability · Published Oct 23, 2026 · Assigned by GitHub_M
CVE-2026-55222Isar: Unprivileged user ownership of trusted repository GPG public keys storage after bootstrap
Medium 5.1
In plain English
A medium-severity security flaw in isar from ilbers. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).
Official description
Isar is an integration system for automated root filesystem generation. In versions 0.11 and newer, /etc/apt/trusted.gpg.d is created manually during bootstrap setup to be able to deploy local keys. By that, the directory is owned by the calling user (the one that executes Isar) instead of root. If the calling user's id is identical to one of an unprivileged user inside the image, this user is able to alter existing keys and deploy new ones, silently breaking the apt repo integrity protection. The issue is has no impact on those images that use an immutable rootfs, or if apt is never invoked. Changing only the keys does not trigger an exploit, it's just one step in a chain. An attacker would also have to manipulate a remote repo or intercept non-secure communication with it. This issue has been patched via commit 29e84ed.
Affected products (as reported)
Weakness: CWE-1290 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/ilbers/isar/security/advisories/GHSA-rq66-pfw5-whqq x_refsource_CONFIRM
- https://github.com/ilbers/isar/commit/29e84ed301c8d25c570300cf82b563b7961392b0 x_refsource_MISC