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CVE-2026-30923

libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings

Published: May 5, 2026Updated: May 7, 2026 Sources: CVE List NVDCWE-125
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.4%
Top 65.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-125

Affected Products

modsecurityowasp
Mixed
Networking Infrastructure / firewall
ModSecurityowasp-modsecurity
On-prem
Networking Infrastructure / firewall
owasposs-projectUSNetworking Infrastructureaka owasp modsecurity core rule set, modsecurity, modsecurity-crs
owasp-modsecurityoss-projectNetworking Infrastructureaka modsecurity, mod_security

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

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

Timeline

Published
May 5, 2026
Last Updated
May 7, 2026

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