CVE-2026-52761: Modsecurity · 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
Affects modsecuritySource GCVE Database
Not known to be exploited · CVSS 5.8 Medium · fixed in 3.0.16 : update modsecurity when convenient.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.0.16
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 10 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10modsecuritypkg:deb/ubuntu/modsecurity?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSmodsecuritypkg:deb/ubuntu/modsecurity?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSmodsecuritypkg:deb/ubuntu/modsecurity?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSmodsecuritypkg:deb/ubuntu/modsecurity?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 20.04 LTSmodsecuritypkg:deb/ubuntu/modsecurity?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade ModSecurity to version 3.0.16 or later, where this vulnerability is fixed. No other mitigation is indicated.
Description
ModSecurity versions 3.0.0 through 3.0.15 contain a vulnerability in the t:utf8toUnicode transformation on i386 architectures. The issue is caused by incorrect use of snprintf with sizeof on a char pointer instead of the unicode buffer length, leading to wrong output. This flaw allows rules that use this transformation to be bypassed on affected systems. The vulnerability is fixed in version 3.0.16.
References
- ubuntu.com/security/CVE-2026-52761 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-52761 (opens in a new tab)
- github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qjgm-7gp4-f8qq (opens in a new tab)
- github.com/owasp-modsecurity/ModSecurity/commit/edcd010814e234d46e2ec55a0f1078ff9d3032e4 (opens in a new tab)
- github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16 (opens in a new tab)