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CVE-2025-48866: ModSecurity has possible DoS vulnerability in sanitiseArg action

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-06-02 · updated 2026-06-17
• Weakness: CWE-1050

Description

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Versions prior to 2.9.10 contain a denial of service vulnerability similar to GHSA-859r-vvv8-rm8r/CVE-2025-47947. The `sanitiseArg` (and `sanitizeArg` - this is the same action but an alias) is vulnerable to adding an excessive number of arguments, thereby leading to denial of service. Version 2.9.10 fixes the issue. As a workaround, avoid using rules that contain the `sanitiseArg` (or `sanitizeArg`) action.

Affected products

• owasp-modsecurity ModSecurity: before 2.9.10 — fixed in 2.9.10

How to fix

Upgrade to a fixed version: owasp-modsecurity ModSecurity 2.9.10. Check the vendor advisory for mitigations.

References

• https://github.com/owasp-modsecurity/ModSecurity/commit/3a54ccea62d3f7151bb08cb78d60c5e90b53ca2e
• https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-859r-vvv8-rm8r
• https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-f82j-8pp7-cw2w
• https://github.com/owasp-modsecurity/ModSecurity/wiki/Reference-Manual-(v2.x)#sanitisearg
• https://lists.debian.org/debian-lts-announce/2025/06/msg00009.html

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