Komari Allows Cross-site WebSocket Hijacking

published 2025-08-12 14 mo ago modified 2026-06-17 4 mo ago also GHSA-q355-h244-969h , GO-2025-3874 , EUVD-2025-25135

cvss: 8.6; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits: 0; none known

Komari is a lightweight, self-hosted server monitoring tool designed to provide a simple and efficient solution for monitoring server performance. Prior to 1.0.4-fix1, WebSocket upgrader has disabled origin checking, enabling Cross-Site WebSocket Hijacking (CSWSH) attacks against authenticated users. Any third party website can send requests to the terminal websocket endpoint with browser's cookies, resulting in remote code execution. This vulnerability is fixed in 1.0.4-fix1.

Patch / fix

fixed in 1 links 3

go github.com/komari-monitor/komari 0.0.0-20250809073044-53171affcaf0

github.com/komari-monitor/komari@d31d12e commit
github.com/komari-monitor/komari@53171af commit
github.com/komari-monitor/komari/releases/tag/1.0.4-fix2 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 14 mo ago (2025-08-18)

Exploit prediction

0.60% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/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 packages

ecosystem	package	affected	fixed in
go	github.com/komari-monitor/komari	<0.0.0-20250809073044-53171affcaf0	0.0.0-20250809073044-53171affcaf0

Affected products

komari-monitor komari

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-1385 Missing Origin Validation in WebSockets

References

Sources

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