CVE-2021-32637

Public Exploit
Authentication bypassed with malformed request URI

Description

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.

Category

10.0
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.20%
Third-Party Advisory github.com Third-Party Advisory github.com
Affected: authelia authelia
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2021-32637?
CVE-2021-32637 has been scored as a critical severity vulnerability.
How to fix CVE-2021-32637?
To fix CVE-2021-32637, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-32637 being actively exploited in the wild?
It is possible that CVE-2021-32637 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-32637?
CVE-2021-32637 affects authelia authelia.
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