CVE-2021-39191
No exploitation reported by the sources we read.
- Published2021-09-03
- WeaknessCWE-601
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
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. 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.
Timeline
dates in UTC- 2021-09-0314:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-24 03:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-39191?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-39191?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 35.x | = 35 | no fix published | NVD |
| 36.x | = 36 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 10.0 | = 10.0 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 2.4 | < 2.4.9.4 | 2.4.9.4 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Packages
- cjoseAlmaLinux:8all versions · fixed in 0.6.1-2.module_el8.6.0+2868+44838709and 1 other package
- mod_auth_openidcAlmaLinux:8all versions · fixed in 2.3.7-11.module_el8.6.0+2868+44838709
Vendor advisories
mod_auth_openidc: open redirect due to target_link_uri parameter not validated
mod_auth_openidc as a component of Red Hat Enterprise Linux 7 · mod_auth_openidc.src as a component of Red Hat Enterprise Linux 7
Red Hat Security Advisory: mod_auth_openidc:2.3 security update
Fix
- Vendor fix Red Hat Product Security RHSA-2022:1823 · 30 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
- No fix planned, says the vendor Red Hat Product Security CVE-2021-39191 · 2 productsOut of support scope
Advisories and patches
- github.comPatch
- github.comRelease Notes
- github.comVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Published
- 2021-09-03
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-39191?
Is CVE-2021-39191 actively exploited?
What is the CVSS score for CVE-2021-39191?
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.