CVE-2025-6395
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 · uneditedA NULL pointer dereference flaw was found in the GnuTLS software in _gnutls_figure_common_ciphersuite().
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 · moderate confidenceA NULL pointer dereference vulnerability exists in GnuTLS within the _gnutls_figure_common_ciphersuite() function during TLS cipher suite negotiation. An attacker could trigger this condition causing a denial of service via application crash.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
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.
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Identify GnuTLS installation and versionRun 'gnutls-cli --version' or 'gnutls-serv --version' to determine the installed GnuTLS version. On systems with multiple GnuTLS libraries, also check '/usr/bin/gnutls-serv' and shared library version via 'ldd' or package manager query such as 'dpkg -l | grep gnutls' or 'rpm -qa | grep gnutls'.Affected if The installed version falls within the affected version range and has not been patched.
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Determine if GnuTLS is used for TLS servicesIdentify applications or services that use GnuTLS for TLS handling. Check running processes for GnuTLS library usage with 'ldd <binary>' or review web server configurations (Apache, nginx) if they link against GnuTLS (libgnutls). Query active network listeners with 'ss -tlnp' or 'netstat -tlnp' to identify TLS-enabled services.Affected if TLS services are running that depend on GnuTLS for cipher suite negotiation.
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Review application logs for TLS handshake failuresExamine system and application logs (/var/log/messages, /var/log/syslog, or application-specific logs) for entries indicating TLS handshake failures, crashes, or aborts occurring during cipher suite negotiation. Search for patterns like 'GNUTLS', 'cipher suite', 'handshake failed', or 'segmentation fault' around the time of service disruption.Affected if Logs show TLS handshake failures or crashes correlated with cipher suite negotiation in GnuTLS-based services.
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Compare installed version to affected rangesOnce the GnuTLS version is identified, compare it against the known affected version range for CVE-2025-6395. If the exact range is unknown, treat any unpatched GnuTLS installation as potentially affected if it participates in TLS cipher suite negotiation.Affected if The installed GnuTLS version is unpatched and within the affected version range for this CVE.
A system is affected if it runs an unpatched GnuTLS version within the vulnerable range AND operates TLS services that perform cipher suite negotiation using the affected _gnutls_figure_common_ciphersuite() function.
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 dataApply the latest GnuTLS security update when released by vendors. If immediate patching is unavailable, monitor for unusual TLS handshake failures and ensure input validation on cipher suite parameters.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-6395 — 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-2025-6395 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
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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