FluentCMS 2026 Stored XSS via SVG Upload in File Management

published 2026-01-29 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-206518

cvss: 4.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

FluentCMS 2026 contains a stored cross-site scripting vulnerability that allows authenticated administrators to upload SVG files with embedded JavaScript via the File Management module. Attackers can upload malicious SVG files that execute JavaScript in the browser of any user accessing the uploaded file URL.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 9 mo ago (2026-01-29)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/fluentcms/FluentCMS/issues/2404 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	4.8	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA	3.1	4.8	CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
CNA	4.0	4.8	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

FluentCMS FluentCMS

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /fluentcms/FluentCMS/issues/2404
issue-tracking, exploit, vendor-advisory
vulncheck.com /advisories/fluentcms-stored-xss-via-svg-upload-in-file-management
third-party-advisory, vdb-entry

Sources

CVE List CVE-2025-15549
NVD CVE-2025-15549

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary