CVE-2026-102631
Received
Received - Intake
authd Session Hijacking via Provider ID Reuse
Vulnerability report for CVE-2026-102631, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-15
Last updated on: 2026-10-15
Assigner: Canonical Ltd.
Description
Description
In authd before 0.7.1, the user identity matching in UpdateUser (internal/users/manager.go) resolves an incoming login by the broker-scoped provider ID, but falls back to matching the username when the provider ID does not belong to any known user, and does not reject a conflicting non-empty provider ID. If an identity provider reassigns an email address, which authd uses as the username, to a new account, the new account inherits the previous user's local UID and home directory on its next login. This allows the new user to access and modify files belonging to the previous user, including credentials such as SSH keys and cloud API tokens, and silently rebinds the local account record to the new identity. As a mitigation, administrators should lock or delete the previous user's local authd account when the corresponding IdP account is removed.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Canonical | authd | 0.1 |
| Canonical | authd | 0.1 |
| Canonical | authd | 0.1 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-287 | When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. |
