Summary
Tilt: Cross-site WebSocket hijacking of the Tilt HUD stream
The Tilt HUD WebSocket (/ws/view) is gated by a CSRF token, but the token is served by an unauthenticated endpoint and the upgrader accepts any client that omits an Origin header. When the HUD is network-exposed, an attacker can open the HUD stream and read the developer's session state.
Details
The upgrader accepts a connection when the csrf query parameter matches a process-wide token (websocketCSRFToken). That token is served as text/plain by an unauthenticated handler (WebsocketToken, mounted at /api/websocket_token), so any reachable caller can fetch it and connect to /ws/view?csrf=<token>. When the parameter does not match, the upgrader falls back to a same-origin check that returns true when the Origin header is absent, so a non-browser client that omits Origin is accepted anyway. The token has no per-session binding.
Conditions for exploitation
- Affected version in
>= 0.24.0, <= 0.37.3. - HUD bound to a non-loopback address (
tilt up --host 0.0.0.0, orTILT_HOSTset). - Network reachability to the listener (default port
10350).
Not affected
- The default loopback-only bind is not reachable from the network.
Workarounds
Use the default loopback bind (omit --host, unset TILT_HOST). No complete workaround short of upgrading for non-loopback deployments.
Impact
An attacker who can reach the HUD listener can open the HUD WebSocket and receive the full view stream, session state, Tiltfile contents, resource statuses, and continued updates, defeating the intended anti-CSWSH protection.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-55883? CVE-2026-55883 is a high-severity security vulnerability in github.com/tilt-dev/tilt (go), affecting versions >= 0.24.0, <= 0.37.3. It is fixed in 0.37.4.
- Which versions of github.com/tilt-dev/tilt are affected by CVE-2026-55883? github.com/tilt-dev/tilt (go) versions >= 0.24.0, <= 0.37.3 is affected.
- Is there a fix for CVE-2026-55883? Yes. CVE-2026-55883 is fixed in 0.37.4. Upgrade to this version or later.
- Is CVE-2026-55883 exploitable, and should I be worried? Whether CVE-2026-55883 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-55883 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-55883? Upgrade
github.com/tilt-dev/tiltto 0.37.4 or later.