Go · github.com/coder/coder/v2
Coder vulnerable to OIDC account takeover via email-based user matching and email_verified bypass
Two flaws in Coder's OIDC login chained into account takeover: email-based user matching fell back to linking by email without checking for an existing link to a different IdP subject and the email_verified claim was only enforced when present as a boolean false so an absent or non-boolean claim was treated as verified.
An attacker who could authenticate at the configured OIDC provider with an email matching a victim's Coder account could log in as that victim and gain full access to their workspaces, templates and resources. This required OIDC authentication, attacker control of a matching email at the IdP and a victim account not yet linked to a different IdP subject.
The fix restricts the email fallback to first-time and legacy linking and defaults email_verified to false when the claim is absent or of an unexpected type.
The fix was backported to all supported release lines:
| Release line | Patched version |
|---|---|
| 2.34 | v2.34.2 |
| 2.33 | v2.33.8 |
| 2.32 | v2.32.7 |
| 2.29 (ESR) | v2.29.17 |
Configure the OIDC provider to disallow self-registration or to require email verification before issuing tokens.
Coder would like to thank Anthropic's Security Team (ANT-2026-22450) for independently disclosing this issue!
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Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.