Mod GnutlsApplication · Apache
CVE-2015-2091
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe authentication hook (mgs_hook_authz) in mod-gnutls 0.5.10 and earlier does not validate client certificates when "GnuTLSClientVerify require" is set, which allows remote attackers to spoof clients via a crafted certificate.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe mod-gnutls Apache module's authentication hook (mgs_hook_authz) in version 0.5.10 and earlier fails to properly validate client certificates even when the GnuTLSClientVerify directive is set to 'require'. This allows remote attackers to craft fraudulent client certificates and impersonate legitimate clients.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Mod GnutlsApplication
<= 0.5.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:N/I:P/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Verify mod_gnutls is loaded in ApacheRun 'apache2ctl -M' or 'httpd -M' and look for mod_gnutls in the loaded modules list, or check for 'LoadModule gnutls_module' in the Apache configuration filesAffected if mod_gnutls is not loaded then the check is not applicable
-
Determine installed mod_gnutls versionRun 'gnutls-cli -v' or check the mod_gnutls package version using your system's package manager (e.g., 'dpkg -l | grep mod-gnutls' or 'rpm -qa | grep gnutls'), or examine the module file modification dateAffected if version is 0.5.1 or earlier, or 0.5.10 or earlier (both version ranges appear in provided documentation)
-
Inspect GnuTLSClientVerify directive configurationSearch Apache configuration files (httpd.conf, ssl.conf, or included config files) for 'GnuTLSClientVerify' and verify its valueAffected if directive is set to 'require' and mod_gnutls version is vulnerable
-
Confirm client certificate authentication is in useLook for 'GnuTLSClientCAFile' or 'GnuTLSCACertificateFile' directives in the Apache configuration, which indicate client certificate authentication is configuredAffected if client certificate authentication is configured with a vulnerable mod_gnutls version and GnuTLSClientVerify set to require
You are affected if mod_gnutls is loaded, the version is 0.5.1 or earlier (or 0.5.10 per the summary), and client certificate authentication is enforced with GnuTLSClientVerify set to require.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade mod-gnutls to a version newer than 0.5.10 where the client certificate validation bug is fixed. If immediate upgrading is not feasible, implement additional authentication layers (such as separate API key or token validation) as a compensating control.
Fix this in Mod Gnutls
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-2091 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-2091 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data