CVE-2026-49757 team-alembic CVE debrief

Who should care

Defenders and administrators of systems using team-alembic AshAuthentication should assess exposure and prioritize verification and remediation to prevent potential account takeover attempts.

Why it matters

The CVE-2026-49757 vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in, posing a critical risk to systems using this authentication mechanism. Defenders and administrators should assess exposure, prioritize verification and remediation, and implement additional security measures to prevent exploitation.

• Account takeover of local users via OAuth2/OIDC sign-in
• Potential unauthorized access to sensitive information
• Need for verification and remediation to prevent exploitation
• Possible lateral movement within the system

Technical summary

The Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in. The vulnerability is caused by the incorrect matching of local users by email address instead of the OpenID Connect iss/sub claim combination. Affected product deployments should be verified for exposure, and owners should prioritize verification and remediation to prevent potential account takeover attempts. The fix resolves users by the (strategy, sub) identity stored in a user identity resource, and only links a new sub to an existing local account by email when the provider's email_verified claim is trusted (trust_email_verified?). This issue affects ash_

Defensive priority

Defenders should prioritize verifying and upgrading to a fixed version of ash_authentication, specifically version 4.14.0 or later, or version 5.0.0-rc.10 or later, and assess exposure of local users via OAuth2/OIDC sign-in.

Recommended defensive actions

• Verify and upgrade to a fixed version of ash_authentication, specifically version 4.14.0 or later, or version 5.0.0-rc.10 or later.
• Assess exposure of local users via OAuth2/OIDC sign-in and ensure proper configuration of the authentication system.
• Monitor for potential account takeover attempts and implement additional security measures to prevent exploitation.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source references provide details on the Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication, allowing account takeover of local users via OAuth2/OIDC sign-in.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.