ModSecurity 2.9.8 Denial of Service via JSON sanitiseMatchedBytes rule
CVE-2025-47947 Published on May 21, 2025
ModSecurity Has Possible DoS Vulnerability
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Versions up to and including 2.9.8 are vulnerable to denial of service in one special case (in stable released versions): when the payload's content type is `application/json`, and there is at least one rule which does a `sanitiseMatchedBytes` action. A patch is available at pull request 3389 and expected to be part of version 2.9.9. No known workarounds are available.
Vulnerability Analysis
CVE-2025-47947 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
Excessive Platform Resource Consumption within a Loop
The software has a loop body or loop condition that contains a control element that directly or indirectly consumes platform resources, e.g. messaging, sessions, locks, or file descriptors.
Products Associated with CVE-2025-47947
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Affected Versions
owasp-modsecurity ModSecurity Version <= 2.9.8 is affected by CVE-2025-47947Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.