CVE-2024-27918 is a high-severity (CVSS 8.2) Improper Input Validation vulnerability in github.com/coder/coder/v2. A fix is available for github.com/coder/coder/v2 — see the affected versions and patch details below.
Coder's OIDC authentication allows email with partially matching domain to register
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-27918.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-27918 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coderReal-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
A vulnerability in Coder's OIDC authentication could allow an attacker to bypass the CODER_OIDC_EMAIL_DOMAIN verification and create an account with an email not in the allowlist. Deployments are only affected if the OIDC provider allows users to create accounts on the provider (such as public providers like google.com).
Details
During OIDC registration, the user's email was improperly validated against the allowed CODER_OIDC_EMAIL_DOMAINs. This could allow a user with a domain that only partially matched an allowed domain to successfully login or register (e.g. [email protected] would match the allowed domain corp.com).
An attacker could register a domain name that exploited this vulnerability and register on a Coder instance with a public OIDC provider.
Impact
Coder instances with OIDC enabled and protected by the CODER_OIDC_EMAIL_DOMAIN configuration.
Coder instances using a private OIDC provider are not affected, as arbitrary users cannot register through a private OIDC provider without first having an account on the provider.
Public OIDC providers (such as google.com without permitted domains set on the OAuth2 App) are impacted.
GitHub authentication and external authentication are not impacted.
Was my deployment impacted?
To check if your deployment was exploited:
- View the audit log on your deployment for unexpected registered users (using the
action:registerfilter) - Check the users list for unexpected users
- Users created via this exploit will have a domain that ends with one of the allowed domains but doesn’t fully match (e.g.
@exploitcorp.cominstead of@corp.com)
- Users created via this exploit will have a domain that ends with one of the allowed domains but doesn’t fully match (e.g.
Patched Versions
This vulnerability is remedied in
- v2.8.4
- v2.7.3
- v2.6.1
All versions prior to these patches are affected by the vulnerability. It is recommended that customers upgrade their deployments as soon as possible if they are utilizing OIDC authentication with the CODER_OIDC_EMAIL_DOMAIN setting.
Thanks
References
https://github.com/coder/coder/security/advisories/GHSA-7cc2-r658-7xpf https://github.com/coder/coder/commit/4439a920e454a82565e445e4376c669e3b89591c https://nvd.nist.gov/vuln/detail/CVE-2024-27918
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.8.0&&< 2.8.4 | 2.8.4go get github.com/coder/coder/v2@v2.8.4 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.7.0&&< 2.7.3 | 2.7.3go get github.com/coder/coder/v2@v2.7.3 |
| 🐹Go | github.com/coder/coder/v2 | all versions | 2.6.1go get github.com/coder/coder/v2@v2.6.1 |
| 🐹Go | github.com/coder/coder | all versions | No fix |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/coder/coder/v2 to 2.8.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27918 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-27918 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-27918. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-27918 in your dependencies?
O3 Security finds CVE-2024-27918 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.