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.
Published: 2026-10-15
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
AI Analysis

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Remediation

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History

Fri, 16 Oct 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 15 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
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.
Title authd: Account takeover via username fallback in identity matching after IdP email reassignment
Weaknesses CWE-287
References
Metrics cvssV4_0

{'score': 5.9, 'vector': 'CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: canonical

Published:

Updated: 2026-10-16T20:16:49.275Z

Reserved: 2026-09-29T15:27:33.452Z

Link: CVE-2026-102631

cve-icon Vulnrichment

Updated: 2026-10-16T20:16:44.185Z

cve-icon NVD

Status : Deferred

Published: 2026-10-15T17:17:10.130

Modified: 2026-10-16T21:17:11.620

Link: CVE-2026-102631

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-16T20:15:13Z

Weaknesses