How severe is CVE-2021-32785?

CVE-2021-32785 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-32785 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-32785?

CVE-2021-32785 primarily affects Openidc Mod Auth Openidc. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-32785?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-32785 published?

CVE-2021-32785 was published on 2021-07-22 and last updated on 2026-06-17.

CVE-2021-32785

CVE-2021-32785 is a medium-severity vulnerability in Openidc Mod Auth Openidc with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-134.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 4.3
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-134
Affected product: Openidc Mod Auth Openidc
Published: 2021-07-22
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-32785?: 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.
How severe is CVE-2021-32785?: CVE-2021-32785 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-32785 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-32785?: CVE-2021-32785 primarily affects Openidc Mod Auth Openidc. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-32785?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-32785 published?: CVE-2021-32785 was published on 2021-07-22 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:openidc:mod_auth_openidc:*:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

More vulnerabilities in Openidc Mod Auth Openidc

CVE-2017-6413 — High (CVSS 8.6): The "OpenID Connect Relying Party and OAuth 2.0 Resource Server" (aka mod_auth_openidc) module before 2.1.6 for the…
CVE-2017-6062 — High (CVSS 8.6): The "OpenID Connect Relying Party and OAuth 2.0 Resource Server" (aka mod_auth_openidc) module before 2.1.5 for the…
CVE-2024-24814 — High (CVSS 7.5): mod_auth_openidc is an OpenID Certified™ authentication and authorization module for the Apache 2.x HTTP server that…
CVE-2023-28625 — High (CVSS 7.5): mod_auth_openidc is an authentication and authorization module for the Apache 2.x HTTP server that implements the…
CVE-2021-20718 — High (CVSS 7.5): mod_auth_openidc 2.4.0 to 2.4.7 allows a remote attacker to cause a denial-of-service (DoS) condition via unspecified…
CVE-2017-6059 — High (CVSS 7.5): Mod_auth_openidc.c in the Ping Identity OpenID Connect authentication module for Apache (aka mod_auth_openidc) before…

All CVEs affecting Openidc Mod Auth Openidc →

Other CWE-134 vulnerabilities

CVE-2012-1851 — Critical (CVSS 10.0): Format string vulnerability in the Print Spooler service in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,…
CVE-2012-0242 — Critical (CVSS 10.0): Format string vulnerability in Advantech/BroadWin WebAccess before 7.0 allows remote attackers to execute arbitrary…
CVE-2011-2475 — Critical (CVSS 10.0): Format string vulnerability in ECTrace.dll in the iMailGateway service in the Internet Mail Gateway in OneBridge Server…
CVE-2011-1568 — Critical (CVSS 10.0): Format string vulnerability in the logText function in shmemmgr9.dll in IGSSdataServer.exe 9.00.00.11074, and…
CVE-2010-4235 — Critical (CVSS 10.0): Format string vulnerability in RealNetworks Helix Server 12.x, 13.x, and 14.x before 14.2, and Helix Mobile Server…
CVE-2011-0270 — Critical (CVSS 10.0): Format string vulnerability in nnmRptConfig.exe in HP OpenView Network Node Manager (OV NNM) 7.51 and 7.53 allows…

Browse all CWE-134 vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

50.255.62.89 (ipv4-addr)
147.15.15.226 (ipv4-addr)
218.4.91.163 (ipv4-addr)
45.84.120.3 (ipv4-addr)
79.137.34.248 (ipv4-addr)
61.76.112.4 (ipv4-addr)
60.199.224.2 (ipv4-addr)
46.253.45.10 (ipv4-addr)