GHSA-c23c-rp3m-vpg3 — envoy
MEDIUMGHSA-c23c-rp3m-vpg3 is a medium-severity (CVSS 5.3) Use After Free vulnerability in github.com/envoyproxy/envoy. No vendor fix is recorded yet; mitigation options are listed below.
Envoy's global rate limit may crash when the response phase limit is enabled and the response phase request is failed directly
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-c23c-rp3m-vpg3.
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-c23c-rp3m-vpg3 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 379,145 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/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
At the rate limit filter, if we enabled the response phase limit with apply_on_stream_done in the rate limit configuration and the response phase limit request fails directly, it may crash Envoy.
Details
When both the request phase limit and response phase limit are enabled, the safe gRPC client instance will be re-used for both the request phase request and response phase request.
But after the request phase request is done, the inner state of the request phase limit request in gRPC client is not cleaned up. When we send the second limit request at response phase, and the second limit request fails directly, we may access the previous request's inner state and result in crash.
PoC
This need to mock the network failure. But we have reproduced by unit test locally.
Impact
This only happens when both the request phase limit and response phase limit are enabled in the rate limit filter, and requires the request to rate limit service fails directly (For example, if from Envoy's perspective, no healthy endpoint for rate limit service may result the request fails directly). That's say, not easy to trigger this.
To workaround
This could be worked around by splitting the rate limit filter. That is, if there is a rate limit filter that contains normal rate limit configuration (request phase limit, without apply_on_stream_done) and also rate limit configuration with apply_on_stream_done (response phase limit). Splitting them into two rate limit filters and ensure one filter only contains normal rate limit configuration (without apply_on_stream_done), and one only contains rate limit configuration with apply_on_stream_done could avoid this problem.
Credit
Mandar Jog ([email protected])
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/envoyproxy/envoy | all versions | No fix |
| 🐹Go | github.com/envoyproxy/envoy | ≥ 1.36.0 | No fix |
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.
Remediation status
No patched version of github.com/envoyproxy/envoy has shipped for GHSA-c23c-rp3m-vpg3 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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-c23c-rp3m-vpg3 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-c23c-rp3m-vpg3. 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-c23c-rp3m-vpg3 in your dependencies?
O3 Security finds GHSA-c23c-rp3m-vpg3 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.