Kuno is Vulnerable to Stored XSS Attack via SVG File Upload

published 2025-10-03 13 mo ago modified 2026-10-08 31 d ago also EUVD-2025-33193

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

KUNO CMS is a fully deployable full-stack blog application. Versions 1.3.13 and below contain validation flaws in its file upload functionality that can be exploited for stored XSS. The upload endpoint only validates file types based on Content-Type headers, lacks file content analysis and extension whitelist restrictions, allowing attackers to upload SVG files containing malicious scripts (disguised as images). When users access the uploaded resource pages, arbitrary JavaScript executes in their browsers. This issue is fixed in version 1.3.14.

Patch / fix

links 2

github.com/xuemian168/kuno@fc486b5 commit
github.com/xuemian168/kuno/releases/tag/v1.3.14 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-10-06)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected products

xuemian168 kuno

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-434 Unrestricted Upload of File with Dangerous Type

References

Sources

CVE List CVE-2025-61681
NVD CVE-2025-61681

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