CVE-2019-19272
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 · uneditedAn issue was discovered in tls_verify_crl in ProFTPD before 1.3.6. Direct dereference of a NULL pointer (a variable initialized to NULL) leads to a crash when validating the certificate of a client connecting to the server in a TLS client/server mutual-authentication setup.
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 confidenceA NULL pointer dereference in the tls_verify_crl function in ProFTPD before version 1.3.6 causes a crash when validating client certificates during TLS mutual authentication. A variable initialized to NULL is directly dereferenced without validation, leading to denial of service.
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< 1.3.6CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 ProFTPD installation and versionRun 'proftpd -v' or 'proftpd -V' to display version information. On Linux, also check 'rpm -q proftpd' or 'dpkg -l proftpd'. Check the binary at /usr/sbin/proftpd if installed from packages.Affected if Installed version is earlier than 1.3.6 (e.g., 1.3.5, 1.3.5a, 1.3.5b, etc.)
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Locate ProFTPD configuration fileCommon locations: /etc/proftpd/proftpd.conf, /etc/proftpd.conf, or /usr/local/etc/proftpd.conf. Check the output of 'proftpd -V' for the default configuration path.Affected if Configuration file exists and TLS settings are defined
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Verify TLS is enabled in configurationSearch the proftpd.conf file for 'TLSEngine' or 'TLSRequired' directives. Use 'grep -i tls /etc/proftpd/proftpd.conf' or similar to locate TLS-related settings.Affected if TLS is enabled (TLSEngine on or TLSRequired on)
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Check if client certificate verification (mutual auth) is enabledSearch the configuration for 'TLSVerifyClient' directive. This setting controls whether the server requests and verifies client certificates during TLS handshake.Affected if TLSVerifyClient is set to 'on', 'required', or 'yes' - this enables the vulnerable code path in tls_verify_crl function
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Check CRL verification configurationSearch for 'TLSCRL' or 'TLSCACertificateFile' directives in the configuration. The tls_verify_crl function is called when the server processes CRL files during client certificate validation.Affected if CRL or CA certificate configuration is present while TLSVerifyClient is enabled
You are affected if running ProFTPD version earlier than 1.3.6 with TLS client certificate verification (TLSVerifyClient) enabled, which triggers the vulnerable tls_verify_crl function during certificate validation.
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 data1.3.6
Upgrade to ProFTPD 1.3.6 or later which contains the fix. Alternatively, disable TLS client certificate verification (mutual authentication) if upgrading is not immediately feasible.
- Consultation2.0 h
- Implementation3.0 h
- Testing6.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2019-19272 — 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-2019-19272 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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- Version or environment caveats, and links to real fixes
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