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CVE-2021-39191

URL Redirection to Untrusted Site ('Open Redirect') in mod_auth_openidc

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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

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

1.74%Up 0.7 points since Sep 4, 2021
90%50%10%1%

What each source reports

CVE List Score used 4.7

URL Redirection to Untrusted Site ('Open Redirect') in mod_auth_openidc

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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
CVE-2021-39191
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-2021-25579 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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
EUVD-2021-25579
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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
CVE-2021-39191
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-7289 6.1

CVE-2021-39191 affecting package mod_auth_openidc for versions less than 2.4.14.2-1

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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
AZL-7289
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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
CVE-2021-39191
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-2021-39191 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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
DEBIAN-CVE-2021-39191
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 7 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-2021-39191 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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the target_link_uri parameter. A patch in version 2.4.9.4 made it so that the OIDCRedirectURLsAllowed setting must be applied to the target_link_uri parameter. There are no known workarounds aside from upgrading to a patched version.

Record
UBUNTU-CVE-2021-39191
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
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-2023:0215-1 No score

Security update for apache2-mod_auth_openidc

This update for apache2-mod_auth_openidc fixes the following issues:

  • CVE-2022-23527: Fixed open redirect in oidc_validate_redirect_url() using tab character (bsc#1206441).
  • CVE-2021-39191: Fixed open redirect issue in target_link_uri parameter (bsc#1190223).
Record
SUSE-SU-2023:0215-1
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
mod_auth_openidc
Azure Linux:2
 before 2.4.14.2-1
2.4.14.2-1
libapache2-mod-auth-openidc
Debian:12
 before 2.4.9.4-1
2.4.9.4-1
libapache2-mod-auth-openidc
Debian:13
 before 2.4.9.4-1
2.4.9.4-1
libapache2-mod-auth-openidc
Debian:14
 before 2.4.9.4-1
2.4.9.4-1
libapache2-mod-auth-openidc
Debian:10
 before 2.3.10.2-1+deb10u3, plus listed versions
2.3.10.2-12.3.10.2-1+deb10u12.3.10.2-1+deb10u2
2.3.10.2-1+deb10u3
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
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
Show 17 moreShow less
Affected packages
PackageAffectedFixed
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 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 SP4
 before 2.3.8-150100.3.22.1
2.3.8-150100.3.22.1
apache2-mod_auth_openidc
SUSE:Linux Enterprise Real Time 15 SP3
 before 2.3.8-150100.3.22.1
2.3.8-150100.3.22.1
apache2-mod_auth_openidc
openSUSE:Leap 15.4
 before 2.3.8-150100.3.22.1
2.3.8-150100.3.22.1
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

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, NVD, OSV

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

In short

CVE-2021-39191 is a medium vulnerability (CVSS 4.7) in Debian Linux, published September 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.74%, the 77th percentile. Fixed in cjose 0.6.1-2.module_el8.6.0+2868+44838709.

References

Show 55 moreShow less
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