GHSA-cf3q-gqg7-3fm9 is a medium-severity (CVSS 6.5) CWE-460 vulnerability in github.com/envoyproxy/envoy. A fix is available for github.com/envoyproxy/envoy — see the affected versions and patch details below.
Envoy crashes when HTTP ext_proc processes local replies
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-cf3q-gqg7-3fm9.
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.
How urgent is this, really
GHSA-cf3q-gqg7-3fm9 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/envoyproxy/envoy🐹github.com/envoyproxy/envoy🐹github.com/envoyproxy/envoy🐹github.com/envoyproxy/envoyReal-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
Envoy's ext_proc HTTP filter is at risk of crashing if a local reply is sent to the external server due to the filter's life time issue. A known situation is the fail of a websocket handshake will trigger a local reply leading to the crash of Envoy.
PoC
If both websocket and ext_proc are enabled, a failed handshake will trigger a local reply, thus ext_proc will crash.
Mitigation
- Disable websocket traffic
- Change the websocket response from backend to always return
101 Switch protocolbased on RFC. - Apply the patch and the ext_proc filter will not send the local reply that is generated by Envoy to the ext_proc server for processing.
- Apply the patch that the router will cancel the upstream requests when sending a local reply.
Impact
Denial of service
Reporter
Vasilios Syrakis Fernando Cainelli
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/envoyproxy/envoy | all versions | 1.30.10go get github.com/envoyproxy/envoy@v1.30.10 |
| 🐹Go | github.com/envoyproxy/envoy | ≥ 1.31.0&&< 1.31.6 | 1.31.6go get github.com/envoyproxy/envoy@v1.31.6 |
| 🐹Go | github.com/envoyproxy/envoy | ≥ 1.32.0&&< 1.32.4 | 1.32.4go get github.com/envoyproxy/envoy@v1.32.4 |
| 🐹Go | github.com/envoyproxy/envoy | ≥ 1.33.0&&< 1.33.1 | 1.33.1go get github.com/envoyproxy/envoy@v1.33.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/envoyproxy/envoy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/envoyproxy/envoy to 1.30.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cf3q-gqg7-3fm9 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-cf3q-gqg7-3fm9 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-cf3q-gqg7-3fm9. 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-cf3q-gqg7-3fm9 in your dependencies?
O3 Security finds GHSA-cf3q-gqg7-3fm9 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.