CVE-2026-54253: TS3 Manager: Reflected XSS via /api/download port parameter steals operator session

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-09-30
Weakness: CWE-79

Description

TS3 Manager is modern web interface for maintaining Teamspeak3 servers. Prior to 2.2.6, the /api/download handler in packages/server/routes/api.js passes the attacker-controlled port query parameter to socket.connect(port, host) and returns the resulting error.message through res.status(400).send(error.message) as text/html without a Content Security Policy. When a logged-in operator follows a crafted top-level link, the reflected value executes in the manager origin. The token cookie set in packages/ui/src/store/modules/query.js lacks HttpOnly, Secure, and an explicit SameSite attribute, allowing the script to read the token and call the autofillform event in packages/server/socket.js. autofillform returns the decoded JWT, including the cleartext ServerQuery password, enabling operator-session hijacking and control of the managed TeamSpeak server when the operator uses administrative ServerQuery credentials. A valid operator session and user interaction are required. This issue is fixed in 2.2.6.

Affected products

joni1802 ts3-manager: before 2.2.6

References

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