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Vulnerability record · CVE-2026-30923 · published 5 May 2026

CVE-2026-30923: Owasp modsecurity out-of-bounds read vulnerability

Owasp · Modsecurity

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.

8.2 CVSS 4.0 High EPSS 0.52% · top 58.5% CWE-125 · Out-of-bounds read
8.2CVSS 4.0 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
25 Jul 2026Last modified by NVD

Description

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.15 PatchProduct
https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g ExploitVendor Advisory
https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.6CVE-2026-52747Owasp modsecurity vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-da…EPSS 0.48%8.6CVE-2024-1019Owasp modsecurity improper input validation vulnerabilityModSecurity / libModSecurity 3.0.0 to 3.0.11 is affected by a WAF bypass for path-based payloads submitted via specially crafted request URLs. ModSec…EPSS 0.69%8.2CVE-2026-42268Owasp modsecurity vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 to before 3.0.15, there is …EPSS 0.49%7.5CVE-2025-48866Owasp modsecurity vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Versions prior to 2.9.10 contain a den…EPSS 0.83%7.5CVE-2023-38285Owasp modsecurity vulnerabilityTrustwave ModSecurity 3.x before 3.0.10 has Inefficient Algorithmic Complexity.EPSS 0.90%7.5CVE-2023-28882Owasp modsecurity uncontrolled resource consumption vulnerabilityTrustwave ModSecurity 3.0.5 through 3.0.8 before 3.0.9 allows a denial of service (worker crash and unresponsiveness) because some inputs cause a seg…EPSS 0.73%7.5CVE-2022-48279Owasp modsecurity interpretation conflict vulnerabilityIn ModSecurity before 2.9.6 and 3.x before 3.0.8, HTTP multipart requests were incorrectly parsed and could bypass the Web Application Firewall. NOTE…EPSS 1.2%7.5CVE-2021-42717Owasp modsecurity vulnerabilityModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in th…EPSS 3.1%

Source: NIST National Vulnerability Database (record CVE-2026-30923), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.