mod_auth_openidc is an authentication/authorization module f… (CVE-2021-32785)

Summary

Vulnerability reported (CVE-2021-32785). Risk of unauthorized operations or information disclosure. Exploitable via mod_auth_openidc.

Original description

The description as published by the source.

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.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-32785 has been found.
Attackers can target a specific entry point like mod_auth_openidc over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2021-32785" on the vendor's site.

CVE-2021-32785
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: mod_auth_openidc / hiredis / OIDCCacheEncrypt
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) has been reported. Attackers reach the vulnerable code path via mod_auth_openidc without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions. Attack surface: mod_auth_openidc / hiredis / OIDCCacheEncrypt.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
2
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2021-32785 libapache2-mod-auth-openidc Fixed in: 2.4.9-1

References

advisory github.com
advisory github.com
advisory lists.debian.org
advisory security.netapp.com
patch github.com
patch oracle.com