CVE-2026-102631 (GCVE-0-2026-102631)
Vulnerability from cvelistv5 – Published: 2026-10-15 16:42 – Updated: 2026-10-16 20:16
VLAI
EPSS
VEX
Title
authd: Account takeover via username fallback in identity matching after IdP email reassignment
Summary
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.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 20:16 UTC
CWE
- CWE-287 - Improper Authentication
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/canonical/authd/pull/2067 | patch |
| https://bugs.launchpad.net/ubuntu/+source/authd/+… | issue-tracking |
| https://ubuntu.com/security/CVE-2026-102631 | vendor-advisory |
Impacted products
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