authd Denial of Service and Local Privilege Escalation

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

authd prior to version 0.6.4 contains a logic error in primary group ID assignment that can lead to local privilege escalation. When a user's primary group ID (GID) differs from their UID, either because the account was created with authd prior to version 0.5.4 or because the primary group was manually changed via the `authctl group set-gid` command, and the user's identity provider record is updated, authd incorrectly resets the user's primary group ID to their UID upon next login. This causes newly created files and directories to be owned by the wrong group, causing denial of service issues, and potentially granting unintended access to other local users and allowing local privilege escalation.

Source published

27 Apr 2026 15:28:48 UTC

Source modified

27 Apr 2026 16:17:10 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 7.3 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

authd prior to version 0.6.4 contains a logic error in primary group ID assignment that can lead to local privilege escalation. When a user's primary group ID (GID) differs from their UID, either because the account was created with authd prior to version 0.5.4 or because the primary group was manually changed via the `authctl group set-gid` command, and the user's identity provider record is updated, authd incorrectly resets the user's primary group ID to their UID upon next login. This causes newly created files and directories to be owned by the wrong group, causing denial of service issues, and potentially granting unintended access to other local users and allowing local privilege escalation.

Source published

Apr 27, 2026, 3:28:48 PM (timezone not stated)

Source modified

Apr 27, 2026, 4:17:10 PM (timezone not stated)

Observed here

1 Nov 2026 11:33:23 UTC

Source terms

ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 7.3 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

authd prior to version 0.6.4 contains a logic error in primary group ID assignment that can lead to local privilege escalation. When a user's primary group ID (GID) differs from their UID, either because the account was created with authd prior to version 0.5.4 or because the primary group was manually changed via the `authctl group set-gid` command, and the user's identity provider record is updated, authd incorrectly resets the user's primary group ID to their UID upon next login. This causes newly created files and directories to be owned by the wrong group, causing denial of service issues, and potentially granting unintended access to other local users and allowing local privilege escalation.

Source published

27 Apr 2026 16:16:46 UTC

Source modified

26 Oct 2026 22:10:00 UTC

Observed here

27 Oct 2026 15:46:40 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.3 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

authd 0.6.0 contains [a bug](https://github.com/canonical/authd/issues/1482) which can lead to an incorrect primary group ID. It affects users whose primary group ID (i.e. the GID in the user record) differs from their UID. There are two ways which can lead to this: 1. The user was created with authd < 0.5.4 (released June 2025). Those users were created with UID != GID. 2. The primary group of the user was modified manually with the authctl utility that is shipped with authd (`authctl group set-gid`). Another condition is that some user information must have changed in the identity provider (else the user record is not updated upon login). If that is the case, the next time an affected user logs in, authd will set their primary group ID to their UID. This could lead to local privileges escalation. Also, files and directories created by those users will be owned by that incorrect primary group, which may grant other local users access to those files which they shouldn't have. Users who are affected by the issue can run this script to fix the primary group ID of all authd users and the file ownership of files in the home directory created with the incorrect GID: ```bash authd_users=$(getent passwd --service authd | cut -d: -f1) for user in $authd_users; do OLD_GID=$(id -g "$user") GID=$(getent group "$user" | cut -d: -f3) if [ -z "$GID" ]; then echo "Warning: could not determine GID for $user, skipping" >&2 continue fi if [ "$OLD_GID" = "$GID" ]; then continue # user not affected fi USER_HOME=$(getent passwd "$user" | cut -d: -f6) echo "Fixing $user: resetting GID from $OLD_GID to $GID" sudo authctl group set-gid "$user" "$OLD_GID" sudo authctl group set-gid "$user" "$GID" sudo chown -R --from=":$OLD_GID" ":$GID" "$USER_HOME" done ``` After applying the fix, affected users must log out and log back in for `id`, `groups`, and new file GID stamping to reflect the corrected primary group. You may also optionally terminate a user's active session with: ```bash sudo loginctl terminate-user "$user" ``` If the users also own files outside their home directory, the ownership of those files might have to be updated as well. Fixed by: https://github.com/canonical/authd/commit/154b428305cb1a7a19c897626fefd09d6dde8b9f

Source published

5 May 2026 22:04:07 UTC

Source modified

25 Jun 2026 19:56:29 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH

authd: Primary group ID is incorrectly set to value of UID in github.com/canonical/authd

Source published

25 Jun 2026 18:43:19 UTC

Source modified

25 Jun 2026 19:45:34 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.