CVE-2019-11387
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 OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-942-APPLICATION-ATTACK-SQLI.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with nested repetition operators.
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 OWASP ModSecurity CRS SQL injection detection rules (REQUEST-942-APPLICATION-ATTACK-SQLI.conf) contain inefficient regular expressions vulnerable to Regular Expression Denial of Service (ReDoS). Attackers can cause excessive CPU consumption by submitting specially crafted SQL injection payloads containing nested repetition operators (e.g., 'a+' or '(a+)+'), triggering catastrophic backtracking in the regex engine.
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>= 3.0.0, <= 3.1.0CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 installed ModSecurity CRS versionCheck the CRS version file or header in the ModSecurity configuration directory (commonly found in modsecurity.d/crs/ or similar path depending on installation). Look for a version indicator in crs-setup.conf or the main CRS configuration.Affected if The installed version is >= 3.0.0 and <= 3.1.0
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Locate the vulnerable SQL injection rules fileFind the file named REQUEST-942-APPLICATION-ATTACK-SQLI.conf in the ModSecurity CRS rules directory. Common paths include /etc/modsecurity/crs/rules/ or within the crs-setup directory.Affected if The file exists and originates from an affected CRS version (3.0.0-3.1.0)
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Inspect regex patterns for nested repetition operatorsOpen REQUEST-942-APPLICATION-ATTACK-SQLI.conf and search for regex patterns containing nested quantifiers such as 'a+', '(a+)+', '.*' nested within groups, or similar constructs that could cause catastrophic backtracking. Look for patterns in SecRule statements with @rx operator.Affected if The file contains patterns with nested repetition operators like '(a+)+', '(.*)+', or similar inefficient constructs
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Confirm SQL injection detection rules are enabledCheck the main CRS configuration (crs-setup.conf) or Apache/Nginx config for SecRuleEnabled or include statements that load the REQUEST-942-APPLICATION-ATTACK-SQLI.conf file. Verify that the rules are actively loaded into ModSecurity.Affected if SQL injection detection rules from this file are loaded and active in the ModSecurity configuration
You are affected if ModSecurity CRS version is between 3.0.0 and 3.1.0 inclusive, the REQUEST-942-APPLICATION-ATTACK-SQLI.conf file exists with nested repetition operator patterns in its regex rules, and those SQL injection detection rules are enabled in your configuration.
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 dataUpdate ModSecurity CRS to a version beyond 3.1.0 which contains patched regex patterns, or manually optimize the vulnerable regex patterns in the affected configuration file to use atomic grouping, possessive quantifiers, or more efficient pattern matching.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-11387 — 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-2019-11387 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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