CVE-2021-32785
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.73%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.73% probability · 85th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-134
- Affected
- openidc/mod auth openidc · netapp/cloud backup · debian/debian linux
- Source
- security-advisories@github.com
References
- https://github.com/zmartzone/mod_auth_openidc/commit/dc672688dc1f2db7df8ad4abebc367116017a449Patch, Third Party Advisory
- https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9Release Notes, Third Party Advisory
- https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-55r8-6w97-xxr4Mitigation, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2023/04/msg00034.htmlMailing List, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210902-0001/Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://github.com/zmartzone/mod_auth_openidc/commit/dc672688dc1f2db7df8ad4abebc367116017a449Patch, Third Party Advisory
- https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9Release Notes, Third Party Advisory
- https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-55r8-6w97-xxr4Mitigation, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2023/04/msg00034.htmlMailing List, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210902-0001/Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.