Authentication bypassed with malformed request URI
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.
Summary
Authelia is a a single sign-on multi-factor portal for web apps. This affects uses who are using nginx ngx_http_auth_request_module with Authelia, it allows a malicious individual who crafts a malformed HTTP request to bypass the authentication mechanism. It additionally could theoretically affect other proxy servers, but all of the ones we officially support except nginx do not allow malformed URI paths. The problem is rectified entirely in v4.29.3. As this patch is relatively straightforward we can back port this to any version upon request. Alternatively we are supplying a git patch to 4.25.1 which should be relatively straightforward to apply to any version, the git patches for specific versions can be found in the references. The most relevant workaround is upgrading. You can also add a block which fails requests that contains a malformed URI in the internal location block.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| authelia | authelia | 4.0.0-alpha1 to before 4.29.3 | 4.29.3 | Patch available | CNA |
| — | github.com/authelia/authelia/v4 (Go) | 4.0.0-alpha1 to before 4.29.3 | 4.29.3 | Patch available | GHSA-68wm-pfjf-wqp6 |
- authelia Vendorauthelia Affected 4.0.0-alpha1 to before 4.29.3 Fixed in 4.29.3 Patch available CNA
- github.com/authelia/authelia/v4 (Go) Vendor— Affected 4.0.0-alpha1 to before 4.29.3 Fixed in 4.29.3 Patch available GHSA-68wm-pfjf-wqp6
Remediation
- Fix · CNA authelia (authelia) Fixed in 4.29.3
- Fix · GHSA-68wm-pfjf-wqp6 github.com/authelia/authelia/v4 (Go) Fixed in 4.29.3 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2021-32637
- 2026-10-03 Alias added: GHSA-68wm-pfjf-wqp6
References
More Authelia vulnerabilities
- TI-2021-10169 Authelia allows open redirects on the logout endpoint CVSS 3.1MEDIUM 5.7
- TI-2026-25918 Authelia: Improper Neutralization of Input During Web Page Generation Leads to Potential Cross-site Scripting CVSS 4.0LOW 0.5
Sources
- CVE-2021-32637 · CVE Program
- CVE-2021-32637 · NVD
- FIRST EPSS
- GHSA-68wm-pfjf-wqp6 · GitHub Advisory Database · CC BY 4.0
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