Security readout for executives and security teams
Plain-English summary
CVE-2021-32791 affects Apache deployments using mod_auth_openidc before 2.4.9. The module encrypted data with repeated AES-GCM parameters, weakening confidentiality protections. The business concern is possible exposure of sensitive authentication-related data, but the published scoring indicates high attack complexity and no integrity or availability impact.
Executive priority
Treat as a scheduled security update, not an emergency unless the module protects highly sensitive or exposed applications. Patch affected authentication gateways promptly because the weakness concerns confidentiality in identity infrastructure.
Technical view
mod_auth_openidc before 2.4.9 used static IV and AAD values with a reused AES-GCM key, creating nonce reuse. The advisory states 2.4.9 changed encryption to dynamic values using cjose AES routines. CVSS 3.1 is 5.9: network reachable, high attack complexity, high confidentiality impact only.
Likely exposure
Exposure is limited to Apache 2.x servers running zmartzone mod_auth_openidc versions earlier than 2.4.9, including downstream packaged versions before their security updates. Systems using the module to protect sensitive applications or login flows deserve priority.
Exploitation context
The provided sources do not show active exploitation, and the CVE is not listed as KEV in the bundle. The risk comes from cryptographic misuse that can weaken confidentiality when the same key and static nonce material are reused.
Researcher notes
Focus validation on version provenance and downstream backports. The key technical issue is AES-GCM nonce reuse from static IV and AAD under a reused key. Do not assume exploitability beyond the advisory and CVSS high-complexity assessment.
Mitigation direction
- Upgrade mod_auth_openidc to 2.4.9 or later.
- Apply fixed Fedora, Debian, Oracle, or other vendor packages where applicable.
- Prioritize internet-facing Apache OIDC relying-party deployments.
- Check vendor guidance for any post-upgrade operational steps.
- Track exceptions for systems that cannot be upgraded promptly.
Validation and detection
- Inventory Apache hosts for loaded mod_auth_openidc modules.
- Confirm deployed mod_auth_openidc versions are 2.4.9 or vendor-fixed builds.
- Review package manager records against relevant distro advisories.
- Verify protected routes still authenticate correctly after patching.
- Record remaining vulnerable instances and compensating controls.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-323: Exact CWE lookup
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Open ATT&CK lookupCWE-330: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-32791 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N2.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9CVE reference
- https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-px3c-6x7j-3r9rCVE reference
- https://github.com/zmartzone/mod_auth_openidc/commit/375407c16c61a70b56fdbe13b0d2c8f11398e92cCVE reference
- FEDORA-2021-e3017c538aCVE reference · vendor-advisory
- FEDORA-2021-17f5cedf66CVE reference · vendor-advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlCVE reference
- [debian-lts-announce] 20230430 [SECURITY] [DLA 3409-1] libapache2-mod-auth-openidc security updateCVE reference · mailing-list
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Reusing a Nonce, Key Pair in Encryption
Reusing a Nonce, Key Pair in Encryption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Use of Insufficiently Random Values
Use of Insufficiently Random Values represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.