GHSA-8fxq-53rx-ph5f: Coder Login Endpoint User Enumeration Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8fxq-53rx-ph5f",
  "modified" : "2026-08-20T18:34:21Z",
  "published" : "2026-08-20T18:34:21Z",
  "aliases" : [ ],
  "summary" : "Coder: Login endpoint user enumeration via timing-defense placeholder in password comparison",
  "details" : "### Summary\n\n`userpassword.Compare()` substituted a placeholder hash derived from the well-known string `\"hunter2\"` when the stored hash was empty. Submitting `\"hunter2\"` therefore matched accounts with no password hash (nonexistent users and SSO-only users) and a subsequent login-type check returned an HTTP 403 that disclosed the account's login type, versus 401 for password users.\n\n> **Note:** Practical exploitation is limited because the timing side channel is noisy and only reveals whether an account exists.\n\n### Impact\n\nAn unauthenticated attacker could enumerate valid accounts and their authentication provider by submitting logins with the password `\"hunter2\"`, distinguishing nonexistent users, SSO users (provider revealed) and password users from the response. This aids credential-stuffing and targeted phishing. No authentication bypass or data access resulted.\n\n### Patches\n\nThe fix derives the timing-defense placeholder from a secure random value that no supplied password can match.\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\nNone.\n\n### References\n\n- Fix: #26205\n\n### Credits\n\nWe'd like to thank Anthropic's Security Team (ANT-2026-22433) for independently disclosing this issue!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.34.0"
      }, {
        "fixed" : "2.34.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.33.0"
      }, {
        "fixed" : "2.33.8"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.30.0"
      }, {
        "fixed" : "2.32.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/coder/coder/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.29.17"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/security/advisories/GHSA-8fxq-53rx-ph5f"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/pull/26205"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/commit/35a7dc8ab9c7f15ce05d963947823ee31224512f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/coder/coder"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/releases/tag/v2.29.17"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/releases/tag/v2.32.7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/releases/tag/v2.33.8"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/coder/coder/releases/tag/v2.34.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-203", "CWE-204" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-20T18:34:21Z",
    "nvd_published_at" : null
  }
}