Use of Externally-Controlled Format String Affecting libapache2-mod-auth-openidc package, versions <2.4.9-1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.56% (78th percentile)

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  • Snyk IDSNYK-DEBIAN12-LIBAPACHE2MODAUTHOPENIDC-1549587
  • published23 Jul 2021
  • disclosed22 Jul 2021

Introduced: 22 Jul 2021

CVE-2021-32785  (opens in a new tab)
CWE-134  (opens in a new tab)

How to fix?

Upgrade Debian:12 libapache2-mod-auth-openidc to version 2.4.9-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libapache2-mod-auth-openidc package and not the libapache2-mod-auth-openidc package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

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 Scores

version 3.1