GHSA-38jh-8h67-m7mj
HIGHChisel's AUTH environment variable not respected in server entrypoint
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/jpillora/chiselReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The Chisel server doesn't ever read the documented AUTH environment variable used to set credentials, which allows any unauthenticated user to connect, even if credentials were set. This advisory is a formalization of a report sent to the maintainer via email.
Details
In the help page for the chisel server subcommand, it mentions an AUTH environment variable that can be set in order to provide credentials that the server should authenticate connections against: https://github.com/jpillora/chisel/blob/3de177432cd23db58e57f376b62ad497cc10840f/main.go#L138.
The issue is that the server entrypoint doesn't ever read the AUTH environment variable. The only place that this happens is in the client entrypoint: https://github.com/jpillora/chisel/blob/3de177432cd23db58e57f376b62ad497cc10840f/main.go#L452
This subverts the expectations set by the documentation, allowing unauthenticated users to connect to a Chisel server, even if auth is attempted to be set up in this manner.
PoC
Run chisel server, first specifying credentials with the AUTH environment variable, then with the --auth argument. In the first case, the server allows connections without authentication, while in the second, the correct behavior is exhibited.
Impact
Anyone who is running the Chisel server, and that is using the AUTH environment variable to specify credentials to authenticate against. Chisel is often used to provide an entrypoint to a private network, which means services that are gated by Chisel may be affected. Additionally, Chisel is often used for exposing services to the internet. An attacker could MITM requests by connecting to a Chisel server and requesting to forward traffic from a remote port.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/jpillora/chisel | all versions | 1.10.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/jpillora/chisel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/jpillora/chisel to 1.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-38jh-8h67-m7mj is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-38jh-8h67-m7mj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-38jh-8h67-m7mj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-38jh-8h67-m7mj in your dependencies?
O3 detects GHSA-38jh-8h67-m7mj across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.