CVE-2021-32785

Format string bug in the Redis cache implementation

Description

mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. When mod_auth_openidc versions prior to 2.4.9 are configured to use an unencrypted Redis cache (`OIDCCacheEncrypt off`, `OIDCSessionType server-cache`, `OIDCCacheType redis`), `mod_auth_openidc` wrongly performed argument interpolation before passing Redis requests to `hiredis`, which would perform it again and lead to an uncontrolled format string bug. Initial assessment shows that this bug does not appear to allow gaining arbitrary code execution, but can reliably provoke a denial of service by repeatedly crashing the Apache workers. This bug has been corrected in version 2.4.9 by performing argument interpolation only once, using the `hiredis` API. As a workaround, this vulnerability can be mitigated by setting `OIDCCacheEncrypt` to `on`, as cache keys are cryptographically hashed before use when this option is enabled.

Category

5.3
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.43%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory debian.org Third-Party Advisory netapp.com Third-Party Advisory oracle.com
Affected: zmartzone mod_auth_openidc
Published at:
Updated at:

References

Link Tags
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-55r8-6w97-xxr4 mitigation third party advisory
https://github.com/zmartzone/mod_auth_openidc/commit/dc672688dc1f2db7df8ad4abebc367116017a449 third party advisory patch
https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9 third party advisory release notes
https://www.oracle.com/security-alerts/cpuapr2022.html third party advisory patch
https://security.netapp.com/advisory/ntap-20210902-0001/ third party advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html third party advisory mailing list

Frequently Asked Questions

What is the severity of CVE-2021-32785?
CVE-2021-32785 has been scored as a medium severity vulnerability.
How to fix CVE-2021-32785?
To fix CVE-2021-32785, 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-2021-32785 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-32785 is being actively exploited. 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-2021-32785?
CVE-2021-32785 affects zmartzone mod_auth_openidc.
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