GHSA-9R87-MVCW-X35F
Vulnerability from github – Published: 2026-07-06 20:52 – Updated: 2026-07-06 20:52Summary
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.
Impact
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.
Patches
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 |
Workarounds
Configure the OIDC provider to disallow self-registration or to require email verification before issuing tokens.
Resources
- Fix: #25712, #25713
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22450) for independently disclosing this issue!
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/coder/coder/v2"
},
"ranges": [
{
"events": [
{
"introduced": "2.34.0"
},
{
"fixed": "2.34.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/coder/coder/v2"
},
"ranges": [
{
"events": [
{
"introduced": "2.33.0"
},
{
"fixed": "2.33.8"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/coder/coder/v2"
},
"ranges": [
{
"events": [
{
"introduced": "2.30.0"
},
{
"fixed": "2.32.7"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/coder/coder/v2"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.29.17"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-55075"
],
"database_specific": {
"cwe_ids": [
"CWE-287",
"CWE-289"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-06T20:52:13Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n\nTwo flaws in Coder\u0027s 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.\n\n### Impact\n\nAn attacker who could authenticate at the configured OIDC provider with an email matching a victim\u0027s 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.\n\n### Patches\n\nThe 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.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |\n| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |\n| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |\n| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |\n\n### Workarounds\n\nConfigure the OIDC provider to disallow self-registration or to require email verification before issuing tokens.\n\n### Resources\n\n- Fix: #25712, #25713\n\n### Credits\n\nCoder would like to thank Anthropic\u0027s Security Team (ANT-2026-22450) for independently disclosing this issue!",
"id": "GHSA-9r87-mvcw-x35f",
"modified": "2026-07-06T20:52:13Z",
"published": "2026-07-06T20:52:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/coder/coder/security/advisories/GHSA-9r87-mvcw-x35f"
},
{
"type": "WEB",
"url": "https://github.com/coder/coder/pull/25712"
},
{
"type": "WEB",
"url": "https://github.com/coder/coder/pull/25713"
},
{
"type": "PACKAGE",
"url": "https://github.com/coder/coder"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "Coder vulnerable to OIDC account takeover via email-based user matching and email_verified bypass"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.