What is CVE-2026-104269?
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, ModSecurity's multipart parser does not apply the RFC 2231 filename* parameter precedence used by common Go, Python, Node.js, and Java application parsers. A Content-Disposition header can provide a benign filename parameter for ModSecurity and a different encoded filename* value that the backend prefers, causing MULTIPART_FILENAME rules and the application to make security decisions on different names. Applications that use the backend-selected name for storage, extension checks, or content-type inference can therefore receive a filename that bypassed WAF inspection. PHP's native multipart parser is not affected by this discrepancy. This issue is fixed in version 3.0.17.
The record classifies CVE-2026-104269 under weakness class CWE-436. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 4 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 8.6 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N - EPSS (FIRST)
- 0.5% probability of exploitation in the next 30 days, higher than 47.3% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 6.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-11-05
Is CVE-2026-104269 being exploited?
It currently carries a trending score of 46 in the Threadlinqs vulnerability feed.
Affected products and versions
- owasp-modsecurity: ModSecurity
How to fix CVE-2026-104269
No vendor patch reference has been recorded for CVE-2026-104269 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-104269
No threat campaign in the Threadlinqs corpus currently references CVE-2026-104269, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.