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CVE-2021-32786

Open Redirect in oidc_validate_redirect_url()

4.7 MediumFix available

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

2.36%Up 1.3 points since Jul 23, 2021
90%50%10%1%

What each source reports

CVE List Score used 4.7

Open Redirect in oidc_validate_redirect_url()

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
CVE-2021-32786
CVSS 3.1
4.7 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Weakness
CWE-601
Updated
2026-11-02
EUVDEUVD-2021-19549 4.7

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
EUVD-2021-19549
CVSS 3.1
4.7 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Updated
2026-11-03
NVD 4.7

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
CVE-2021-32786
CVSS 3.1
4.7 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
5.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:N
Weakness
CWE-601
Updated
2026-11-02
OSVAZL-6480 6.1

CVE-2021-32786 affecting package httpd for versions less than 2.4.52-1

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
AZL-6480
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSV 6.1

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
CVE-2021-32786
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-32786 6.1

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
DEBIAN-CVE-2021-32786
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
Show 11 moreShow less
OSVRHSA-2022:1823 6.1

Red Hat Security Advisory: mod_auth_openidc:2.3 security update

Record
RHSA-2022:1823
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVRLSA-2022:1823 6.1

Moderate: mod_auth_openidc:2.3 security update

The mod_auth_openidc is an OpenID Connect authentication module for Apache HTTP Server. It enables an Apache HTTP Server to operate as an OpenID Connect Relying Party and/or OAuth 2.0 Resource Server.

Security Fix(es):

  • mod_auth_openidc: open redirect in oidc_validate_redirect_url() (CVE-2021-32786)

  • mod_auth_openidc: hardcoded static IV and AAD with a reused key in AES GCM encryption (CVE-2021-32791)

  • mod_auth_openidc: XSS when using OIDCPreservePost On (CVE-2021-32792)

  • mod_auth_openidc: open redirect due to target_link_uri parameter not validated (CVE-2021-39191)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 8.6 Release Notes linked from the References section.

Record
RLSA-2022:1823
CVSS 3.0
6.1 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2021-32786 4.7

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. In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring mod_auth_openidc to only allow redirection whose destination matches a given regular expression.

Record
UBUNTU-CVE-2021-32786
CVSS 3.1
4.7 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVALSA-2022:1823 No score

Moderate: mod_auth_openidc:2.3 security update

The mod_auth_openidc is an OpenID Connect authentication module for Apache HTTP Server. It enables an Apache HTTP Server to operate as an OpenID Connect Relying Party and/or OAuth 2.0 Resource Server.

Security Fix(es):

  • mod_auth_openidc: open redirect in oidc_validate_redirect_url() (CVE-2021-32786)

  • mod_auth_openidc: hardcoded static IV and AAD with a reused key in AES GCM encryption (CVE-2021-32791)

  • mod_auth_openidc: XSS when using OIDCPreservePost On (CVE-2021-32792)

  • mod_auth_openidc: open redirect due to target_link_uri parameter not validated (CVE-2021-39191)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

Record
ALSA-2022:1823
Updated
2026-11-02
OSVMGASA-2021-0452 No score

Updated apache-mod_auth_openidc packages fix security vulnerability

In versions prior to 2.4.9, oidc_validate_redirect_url() does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. (CVE-2021-32786)

In mod_auth_openidc before version 2.4.9, the AES GCM encryption in mod_auth_openidc uses a static IV and AAD. It is important to fix because this creates a static nonce and since aes-gcm is a stream cipher, this can lead to known cryptographic issues, since the same key is being reused. (CVE-2021-32791)

In mod_auth_openidc before version 2.4.9, there is an XSS vulnerability in when using OIDCPreservePost On. (CVE-2021-32792)

Record
MGASA-2021-0452
Updated
2026-11-02
OSVopenSUSE-SU-2021:1277-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • CVE-2021-32785: format string bug via hiredis (bsc#1188638)
  • CVE-2021-32786: open redirect in logout functionality (bsc#1188639)
  • CVE-2021-32791: Hardcoded static IV and AAD with a reused key in AES GCM encryption (bsc#1188849)
  • CVE-2021-32792: XSS when using OIDCPreservePost On (bsc#1188848)

This update was imported from the SUSE:SLE-15-SP1:Update update project.

Record
openSUSE-SU-2021:1277-1
Updated
2026-11-02
OSVopenSUSE-SU-2021:3020-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • CVE-2021-32785: format string bug via hiredis (bsc#1188638)
  • CVE-2021-32786: open redirect in logout functionality (bsc#1188639)
  • CVE-2021-32791: Hardcoded static IV and AAD with a reused key in AES GCM encryption (bsc#1188849)
  • CVE-2021-32792: XSS when using OIDCPreservePost On (bsc#1188848)
Record
openSUSE-SU-2021:3020-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:10624-1 No score

apache2-mod_auth_openidc-2.4.9.4-1.2 on GA media

These are all security issues fixed in the apache2-mod_auth_openidc-2.4.9.4-1.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10624-1
Updated
2026-11-02
OSVSUSE-SU-2021:3020-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • CVE-2021-32785: format string bug via hiredis (bsc#1188638)
  • CVE-2021-32786: open redirect in logout functionality (bsc#1188639)
  • CVE-2021-32791: Hardcoded static IV and AAD with a reused key in AES GCM encryption (bsc#1188849)
  • CVE-2021-32792: XSS when using OIDCPreservePost On (bsc#1188848)
Record
SUSE-SU-2021:3020-1
Updated
2026-11-02
OSVSUSE-SU-2021:3352-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • CVE-2021-32785: format string bug via hiredis (bsc#1188638)
  • CVE-2021-32786: open redirect in logout functionality (bsc#1188639)
  • CVE-2021-32791: Hardcoded static IV and AAD with a reused key in AES GCM encryption (bsc#1188849)
  • CVE-2021-32792: XSS when using OIDCPreservePost On (bsc#1188848)
  • CVE-2021-39191: open redirect issue in target_link_uri parameter (bsc#1190223)
Record
SUSE-SU-2021:3352-1
Updated
2026-11-02
OSVSUSE-SU-2025:4532-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • Update to 2.4.17.1 (bsc#1248806 / PED-14130).
  • Remove many patches, as they've been merged upstream.
Record
SUSE-SU-2025:4532-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
cjose
AlmaLinux:8
 before 0.6.1-2.module_el8.6.0+2868+44838709
0.6.1-2.module_el8.6.0+2868+44838709
cjose-devel
AlmaLinux:8
 before 0.6.1-2.module_el8.6.0+2868+44838709
0.6.1-2.module_el8.6.0+2868+44838709
mod_auth_openidc
AlmaLinux:8
 before 2.3.7-11.module_el8.6.0+2868+44838709
2.3.7-11.module_el8.6.0+2868+44838709
httpd
Azure Linux:2
 before 2.4.52-1
2.4.52-1
libapache2-mod-auth-openidc
Debian:12
 before 2.4.9-1
2.4.9-1
libapache2-mod-auth-openidc
Debian:13
 before 2.4.9-1
2.4.9-1
libapache2-mod-auth-openidc
Debian:14
 before 2.4.9-1
2.4.9-1
libapache2-mod-auth-openidc
Debian:10
 before 2.3.10.2-1+deb10u2, plus listed versions
2.3.10.2-12.3.10.2-1+deb10u1
2.3.10.2-1+deb10u2
apache-mod_auth_openidc
Mageia:8
 before 2.4.9.4-1.mga8
2.4.9.4-1.mga8
cjose
Red Hat:enterprise_linux:8::appstream
 before 0:0.6.1-2.module+el8+2454+f890a43a
0:0.6.1-2.module+el8+2454+f890a43a
Show 20 moreShow less
Affected packages
PackageAffectedFixed
cjose-debuginfo
Red Hat:enterprise_linux:8::appstream
 before 0:0.6.1-2.module+el8+2454+f890a43a
0:0.6.1-2.module+el8+2454+f890a43a
cjose-debugsource
Red Hat:enterprise_linux:8::appstream
 before 0:0.6.1-2.module+el8+2454+f890a43a
0:0.6.1-2.module+el8+2454+f890a43a
cjose-devel
Red Hat:enterprise_linux:8::appstream
 before 0:0.6.1-2.module+el8+2454+f890a43a
0:0.6.1-2.module+el8+2454+f890a43a
mod_auth_openidc
Red Hat:enterprise_linux:8::appstream
 before 0:2.3.7-11.module+el8.6.0+14082+b6f23e95
0:2.3.7-11.module+el8.6.0+14082+b6f23e95
mod_auth_openidc-debuginfo
Red Hat:enterprise_linux:8::appstream
 before 0:2.3.7-11.module+el8.6.0+14082+b6f23e95
0:2.3.7-11.module+el8.6.0+14082+b6f23e95
mod_auth_openidc-debugsource
Red Hat:enterprise_linux:8::appstream
 before 0:2.3.7-11.module+el8.6.0+14082+b6f23e95
0:2.3.7-11.module+el8.6.0+14082+b6f23e95
cjose
Rocky Linux:8
 before 0:0.6.1-2.module+el8.3.0+129+2feafa46
0:0.6.1-2.module+el8.3.0+129+2feafa46
mod_auth_openidc
Rocky Linux:8
 before 0:2.3.7-11.module+el8.6.0+840+73eca44e
0:2.3.7-11.module+el8.6.0+840+73eca44e
apache2-mod_auth_openidc
SUSE:Linux Enterprise Module for Server Applications 15 SP2
 before 2.3.8-3.15.1
2.3.8-3.15.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Module for Server Applications 15 SP3
 before 2.3.8-3.15.1
2.3.8-3.15.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Server 12 SP5
 before 2.4.0-3.23.1
2.4.0-3.23.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
 before 2.4.0-3.23.1
2.4.0-3.23.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Module for Server Applications 15 SP6
 before 2.4.17.1-150600.16.14.1
2.4.17.1-150600.16.14.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Module for Server Applications 15 SP7
 before 2.4.17.1-150600.16.14.1
2.4.17.1-150600.16.14.1
apache2-mod_auth_openidc
openSUSE:Leap 15.6
 before 2.4.17.1-150600.16.14.1
2.4.17.1-150600.16.14.1
libapache2-mod-auth-openidc
Ubuntu:18.04:LTS
 All versions, plus listed versions
2.1.6-12.3.1-22.3.2-12.3.2-1build12.3.3-1build1
 None known
libapache2-mod-auth-openidc
Ubuntu:20.04:LTS
 All versions, plus listed versions
2.3.10.2-12.4.0.4-12.4.1-1
 None known
apache2-mod_auth_openidc
openSUSE:Leap 15.2
 before 2.3.8-lp152.5.6.1
2.3.8-lp152.5.6.1
apache2-mod_auth_openidc
openSUSE:Leap 15.3
 before 2.3.8-3.15.1
2.3.8-3.15.1
apache2-mod_auth_openidc
openSUSE:Tumbleweed
 before 2.4.9.4-1.2
2.4.9.4-1.2

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-32786 is a medium vulnerability (CVSS 4.7) in Fedoraproject Fedora, published July 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.36%, the 83rd percentile. Fixed in cjose 0.6.1-2.module_el8.6.0+2868+44838709.

References

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