CVE-2026-55884: Tilt: Missing authentication on the network-exposed Tilt HUD server

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 42: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 42% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes github.com/tilt-dev/tilt (Go) >= 0.20.8, <= 0.37.3, fixed in 0.37.4. Check your lockfile, including transitive dependencies.

What it is

Tilt defines dev environments as code for microservice apps on Kubernetes. From 0.20.8 through 0.37.3, the Tilt HUD HTTP server registers handlers on a gorilla/mux router with no authenticating middleware. When the HUD is bound to a non-loopback address, an unauthenticated network caller can trigger developer-defined resources, tamper with Tiltfile arguments, read full engine state including the session token, and invoke apiserver resources through the token-attaching /proxy handler. This issue is fixed in version 0.37.4.

From the GitHub advisory

Summary The Tilt HUD HTTP server exposes state-changing and sensitive-read endpoints with no authentication. When the HUD is bound to a non-loopback address, a network attacker can trigger the developer's pre-defined Tiltfile resources, tamper with Tiltfile arguments, read full engine state including the session token, and reach the Tilt apiserver through a token-attaching proxy.

Details The HUD server registers its handlers on a gorilla/mux router with no authenticating middleware. The cookieWrapper helper emits the Tilt-Token cookie but never validates it, and is attached only to the static-asset prefix.

Impact An unauthenticated network caller can force any developer-defined resource to run on the host as the tilt user (choosing which and when, not the command text), set arbitrary Tiltfile arguments, disclose the session token and full engine state, and invoke apiserver resources via the loopback-token proxy. Because tilt up runs with the developer's privileges and credentials, the impact reaches the developer's environment and cluster.

Conditions for exploitation - Affected version in >= 0.20.8,

Not affected - The default loopback-only bind is not reachable from the network.

Weakness type: CWE-306.

Product: github.com/tilt-dev/tilt (Go) · Assigned by: GitHub_M · Published: 2026-07-10

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.50% probability of exploitation activity in the next 30 days; percentile 42.

Timeline

• 2026-06-19 — GitHub-reviewed advisory GHSA-c73q-8xxr-rgqm published (critical)
• 2026-07-10 — CVE record published by GitHub_M
• 2026-07-29 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-c73q-8xxr-rgqm github.com
2. CVE.org record CVE-2026-55884 cve.org
3. NVD entry CVE-2026-55884 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical Go advisories · Today’s Security Digest