CVE-2026-55076

CVE-2026-55076 is a high-severity improper authentication vulnerability in github.com/coder/coder/v2 (go), affecting versions >= 2.34.0, < 2.34.2. It is fixed in 2.34.2, 2.33.8, 2.32.7, 2.29.17.

Summary

Coder's OIDC email_verified type coercion bypass enables account takeover via unverified email linking

Full technical description

Coder's OIDC callback checked email_verified with a direct Go bool type assertion. When an IdP returned the claim as a non-boolean (for example the string "false") or omitted it, the assertion failed open and the email was treated as verified. Combined with an unconditional email-based account fallback, this enabled account takeover.

Workarounds

Ensure the IdP returns email_verified as a native JSON boolean. The email-fallback linking issue has no configuration workaround; upgrading is required.

Resources

  • Fix: #25712, #25713

Credits

Coder would like to thank Anthropic's Security Team (ANT-2026-22444) for independently disclosing this issue!

Impact

An attacker who registered a victim's email at a compatible IdP without verifying it could log in via OIDC and be matched to the victim's existing Coder account, receiving a session for that account. No prior authentication to Coder was required and the result was full account takeover.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2026-55076 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.34.2, 2.33.8, 2.32.7, 2.29.17); upgrading removes the vulnerable code path.

Affected versions

github.com/coder/coder/v2 (>= 2.34.0, < 2.34.2) github.com/coder/coder/v2 (>= 2.33.0, < 2.33.8) github.com/coder/coder/v2 (>= 2.30.0, < 2.32.7) github.com/coder/coder/v2 (< 2.29.17)

Security releases

github.com/coder/coder/v2 → 2.34.2 (go) github.com/coder/coder/v2 → 2.33.8 (go) github.com/coder/coder/v2 → 2.32.7 (go) github.com/coder/coder/v2 → 2.29.17 (go)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

The fix coerces email_verified across bool, string and numeric types (fail-closed) and blocks the email fallback when the matched user already has a different linked IdP subject.

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

Frequently Asked Questions

  1. What is CVE-2026-55076? CVE-2026-55076 is a high-severity improper authentication vulnerability in github.com/coder/coder/v2 (go), affecting versions >= 2.34.0, < 2.34.2. It is fixed in 2.34.2, 2.33.8, 2.32.7, 2.29.17. The application does not adequately verify the identity of a user, device, or process before granting access.
  2. How severe is CVE-2026-55076? CVE-2026-55076 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
  3. Which versions of github.com/coder/coder/v2 are affected by CVE-2026-55076? github.com/coder/coder/v2 (go) versions >= 2.34.0, < 2.34.2 is affected.
  4. Is there a fix for CVE-2026-55076? Yes. CVE-2026-55076 is fixed in 2.34.2, 2.33.8, 2.32.7, 2.29.17. Upgrade to this version or later.
  5. Is CVE-2026-55076 exploitable, and should I be worried? Whether CVE-2026-55076 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
  6. What actually determines whether CVE-2026-55076 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
  7. How do I fix CVE-2026-55076?
    • Upgrade github.com/coder/coder/v2 to 2.34.2 or later
    • Upgrade github.com/coder/coder/v2 to 2.33.8 or later
    • Upgrade github.com/coder/coder/v2 to 2.32.7 or later
    • Upgrade github.com/coder/coder/v2 to 2.29.17 or later

Other vulnerabilities in github.com/coder/coder/v2

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