GHSA-w9mr-28mw-j8hg
Hop-by-hop abuse to malform header mutator
Blast Radius
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Description
Impact
Downstream services relying on the presence of headers set by the header mutator could be exploited. A client can drop the header set by the header mutator by including that header's name in the Connection header. Example minimal config:
- id: 'example'
upstream:
url: 'https://example.com'
match:
url: 'http://127.0.0.1:4455/'
methods:
- GET
authenticators:
- handler: anonymous
authorizer:
handler: allow
mutators:
- handler: header
config:
headers:
X-Subject: {{ .Subject }}
curl -H "Connection: close,x-subject" http://127.0.0.1:4455/
The X-Subject header will not arrive at the downstream server. It is completely dropped. In case the downstream server handles such a request in an unexpected way, an attacker can exploit this, assuming they know or guess the internal header name.
Patches
c5cc7f736dc84185034be4356057d1c7a656d797
Workarounds
The downstream server should handle the case that an expected header is not set by responding with an appropriate error.
References
See background info in https://github.com/golang/go/issues/50580
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ory/oathkeeper | all versions | 0.40.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ory/oathkeeper. 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/ory/oathkeeper to 0.40.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w9mr-28mw-j8hg 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-w9mr-28mw-j8hg 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-w9mr-28mw-j8hg. 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-w9mr-28mw-j8hg in your dependencies?
O3 detects GHSA-w9mr-28mw-j8hg across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.