# GHSA-55f6-4pr5-c7m5: Kahi has privilege-drop and socket/log permission issues

> Kahi process supervisor fails to drop privileges correctly and exposes sockets, allowing local attackers to escalate privileges or access services.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Jun 2026
- **Also known as:** GO-2026-5847

## What is GHSA-55f6-4pr5-c7m5?

GHSA-55f6-4pr5-c7m5 is a vulnerability in github.com/kahiteam/kahi, published on 30 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Kahi releases up to and including v0.1.0-alpha.8 contain three privilege/permission issues, all fixed in v0.1.0-alpha.9. They were identified in a full-codebase security review on 2026-05-26.

## Affected versions
All releases <= v0.1.0-alpha.8.

## Patched version
v0.1.0-alpha.9.

## Details

### 1. Per-process privilege drop not applied (High)
A process configured with `user = "uid:gid"` had its credential resolved but never attached to the spawned child, so the process ran with the supervisor's inherited privileges (root, when the supervisor runs as root) instead of the configured lower-privilege user. The intended privilege isolation did not occur, and no error was raised.

### 2. Privilege drop did not reset supplementary groups (Medium)
When the daemon dropped privileges it set the primary gid and uid but never called setgroups(2), so the launching user's supplementary groups (for example `docker`, which is root-equivalent) remained active after the drop and were inherited by child processes.

### 3. FastCGI unix socket world-accessible by default (Medium)
A FastCGI unix-domain socket was chmod-ed only when `socket_mode` was explicitly configured. With `socket_mode` unset the socket kept the umask-dependent default (commonly world-accessible), allowing any local user to connect to it.

## Remediation
Upgrade to v0.1.0-alpha.9. Privilege handling is now fail-closed: the configured credential is applied or the process refuses to start, supplementary groups are reset via setgroups before setgid/setuid, and FastCGI unix sockets default to 0700.

## Workarounds (for <= v0.1.0-alpha.8)
- Do not rely on per-process `user`; run the supervisor directly as the intended unprivileged user.
- Set an explicit restrictive `socket_mode` on FastCGI programs.
- Avoid running the supervisor as root where possible.

## Which versions are affected by GHSA-55f6-4pr5-c7m5?

3 open source packages ship an affected version, including github.com/kahiteam/kahi.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/kahiteam/kahi` | Go | All versions | 0.1.0-alpha.9 |
| `github.com/kahiteam/kahi` | Go | All versions | 0.1.0-alpha.9 |
| `github.com/kahiteam/kahi` | Go | All versions | 0.1.0-alpha.9 |

## How do I fix GHSA-55f6-4pr5-c7m5?

Upgrade github.com/kahiteam/kahi to 0.1.0-alpha.9 or later.

## Is GHSA-55f6-4pr5-c7m5 being exploited?

There is no known exploitation of GHSA-55f6-4pr5-c7m5 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-55f6-4pr5-c7m5 and fix it if it is affected.

What it is: GHSA-55f6-4pr5-c7m5 is a vulnerability in github.com/kahiteam/kahi, published on 30 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-55f6-4pr5-c7m5 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/kahiteam/kahi (Go): affected all versions; fixed in 0.1.0-alpha.9
- github.com/kahiteam/kahi (Go): affected all versions; fixed in 0.1.0-alpha.9
- github.com/kahiteam/kahi (Go): affected all versions; fixed in 0.1.0-alpha.9

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-55f6-4pr5-c7m5/ (Markdown: https://insights.sbomify.com/GHSA-55f6-4pr5-c7m5/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-55f6-4pr5-c7m5

---
From sbomify Insights: https://insights.sbomify.com/GHSA-55f6-4pr5-c7m5/
Summaries are generated and may contain mistakes; the official description above is the record.