ModSecurity is a widely deployed WAF across Apache/IIS/Nginx; this parsing mismatch enables WAF bypass for file uploads and can lead to backend compromise, impacting many web apps and servers.
CVE-2026-104269
ModSecurity filename parsing mismatch allows WAF bypass and malicious file uploads
Is CVE-2026-104269 being exploited?
Not confirmed. CVE-2026-104269 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.57% probability of exploitation in the next 30 days.
How severe is CVE-2026-104269?
CVE-2026-104269 is rated High with a CVSS score of 8.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-104269?
Yes. A fix has been recorded for CVE-2026-104269. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-104269 affect?
CVE-2026-104269 affects ModSecurity 3.0.0 - 3.0.16 (fixed in 3.0.17), Deployments on Apache, IIS, Nginx using ModSecurity 3.x. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-104269?
Upgrade to ModSecurity v3.0.17; validate backend filename/content-type checks; review upload logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Content-Disposition filename/filename* mismatch lets attackers bypass WAF MULTIPART_FILENAME checks, enabling uninspected malicious file uploads and possible RCE or data compromise.
Immediate action required
- affected>= 3.0.0 and < 3.0.17
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
timeline
- 5 Nov 2026Published
- 5 Nov 2026CVE record last updated · same day later
- 6 Nov 2026Analysed by vulneraibility.com · 1 day later
also known as
- Linkgithub.com /owasp-modsecurity/ModSecurity/security/advisories/GHSA-5pww-8rfg-9crf
- Linkgithub.com /owasp-modsecurity/ModSecurity/commit/463db0c840fa27bfba095b0406a63004a12884b0
- Linkgithub.com /owasp-modsecurity/ModSecurity/commit/c6bd53d2dd96766b3afdc35d9929ebb20925d13d
- Linkgithub.com /owasp-modsecurity/ModSecurity/releases/tag/v2.9.15
- Linkgithub.com /owasp-modsecurity/ModSecurity/releases/tag/v3.0.17
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- FIRST EPSS: exploit probability and percentile
- OSV: advisory aliases and downstream package versions
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.