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VulnerabilityPublished

CVE-2025-55300: komari · Cross-site Scripting

Affects komariSource CVE Database V5

0

Not known to be exploited · CVSS 8.6 High · fixed in 1.0.4 : patch komari soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 4.0 base score
8.6High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.0.4
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Aug 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
komari-monitor komariAffected
  • =1.0.4-fix1
Fixed in–

AI-suggested

  1. Immediate upgrade of all Komari installations to version 1.0.4-fix1 or later, where the origin checking on the WebSocket upgrader is restored and the vulnerability is fixed.
  2. Implement strict Content Security Policy (CSP) headers on web interfaces to limit the ability of malicious sites to execute scripts or initiate WebSocket connections.
  3. Restrict network access to Komari’s WebSocket endpoints to trusted IP ranges or VPNs to reduce exposure to external attackers.
  4. Monitor WebSocket traffic and logs for unusual or unauthorized connection attempts, especially from unexpected origins.
  5. Educate users about the risks of visiting untrusted websites while authenticated to Komari monitoring interfaces.
  6. Employ Web Application Firewalls (WAFs) with rules to detect and block suspicious WebSocket upgrade requests lacking proper origin headers.
  7. Regularly audit and review server monitoring tools and their configurations to ensure security best practices are followed. These steps go beyond generic patching by adding layered defenses to reduce the attack surface and detect exploitation attempts.

Description

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.

References

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