Bug 2499254 (CVE-2026-52761)

Summary: CVE-2026-52761 ModSecurity: ModSecurity: Web Application Firewall rules bypass due to incorrect UTF-8 to Unicode transformation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in ModSecurity, an open-source web application firewall (WAF). The `t:utf8toUnicode` transformation function, responsible for converting UTF-8 encoded characters to Unicode, generates incorrect output on i386 architectures. This vulnerability allows an attacker to bypass WAF rules, potentially enabling malicious requests to reach the protected application. The consequence is a moderate integrity loss due to the circumvention of security controls.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2499330, 2499331, 2499332, 2499333    
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Description OSIDB Bzimport 2026-07-10 22:02:19 UTC
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 through 3.0.15, the t:utf8toUnicode transformation in src/actions/transformations/utf8_to_unicode.cc produces wrong output on i386 architecture because snprintf uses sizeof on a char pointer rather than the length of the unicode buffer, allowing rules that use this transformation to be bypassed on i386 architecture. This issue is fixed in version 3.0.16.