WAF bypass via premature URL decoding
Published Jan 30, 2024 · Updated Jun 17, 2025
Improper input validation in OWASP ModSecurity 3.0.0 through 3.0.11 allows remote attackers to bypass WAF path rules via crafted URLs. The request-URI processor decodes %3F into a question mark before splitting the path and query, truncating REQUEST_FILENAME and REQUEST_BASENAME before rule inspection. The bypass requires a back-end that constructs queries or commands from URI path components, and it can conceal SQL injection, cross-site scripting, or command payloads from affected rules.
Summary
What happened
Improper input validation in OWASP ModSecurity 3.0.0 through 3.0.11 allows remote attackers to bypass WAF path rules via crafted URLs. The request-URI processor decodes %3F into a question mark before splitting the path and query, truncating REQUEST_FILENAME and REQUEST_BASENAME before rule inspection. The bypass requires a back-end that constructs queries or commands from URI path components, and it can conceal SQL injection, cross-site scripting, or command payloads from affected rules.
The record
- CVE
- CVE-2024-1019
- Published
- Jan 30, 2024
- Updated
- Jun 17, 2025
- Vendor
- OWASP ModSecurity
- Product
- ModSecurity
- Classifications
- CWE-20, CAPEC-152, T1562.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 30, 2024CVE publishedPublication date reported by the CVE source.
- Jun 17, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3.0.0 <=3.0.11
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- OWASP encoded-question-mark WAF bypass exampleproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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