GHSA-8fxq-53rx-ph5f is a low-severity (CVSS 3.7) vulnerability in github.com/coder/coder/v2. O3 Security confirms whether GHSA-8fxq-53rx-ph5f is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Coder: Login endpoint user enumeration via timing-defense placeholder in password comparison
Real-World Exposure
github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coder/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
Note: Practical exploitation is limited because the timing side channel is noisy and only reveals whether an account exists.
Impact
An 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.
Patches
The fix derives the timing-defense placeholder from a secure random value that no supplied password can match.
The fix was backported to all supported release lines:
Workarounds
None.
References
- Fix: #26205
Credits
We'd like to thank Anthropic's Security Team (ANT-2026-22433) for independently disclosing this issue!
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.34.0&&< 2.34.2 | 2.34.2 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.33.0&&< 2.33.8 | 2.33.8 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.30.0&&< 2.32.7 | 2.32.7 |
| 🐹Go | github.com/coder/coder/v2 | all versions | 2.29.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/coder/coder/v2. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/coder/coder/v2 to 2.34.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8fxq-53rx-ph5f is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-8fxq-53rx-ph5f is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-8fxq-53rx-ph5f. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8fxq-53rx-ph5f in your dependencies?
O3 detects GHSA-8fxq-53rx-ph5f across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.