GHSA-496j-2rq6-j6cc — grpcio
HIGHGHSA-496j-2rq6-j6cc is a high-severity (CVSS 7.5) CWE-789 vulnerability in grpcio. A fix is available for grpcio — see the affected versions and patch details below.
Excessive Iteration in gRPC
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-496j-2rq6-j6cc.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-496j-2rq6-j6cc by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
grpcio🐍grpcio🐍grpcio🐍grpcio💎grpc💎grpc💎grpc💎grpcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks:
- Unbounded memory buffering in the HPACK parser
- Unbounded CPU consumption in the HPACK parser
The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client.
The unbounded memory buffering bugs:
- The header size limit check was behind the string reading code, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb.
- HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse.
- gRPC’s metadata overflow check was performed per frame, so that the following sequence of frames could cause infinite buffering: HEADERS: containing a: 1 CONTINUATION: containing a: 2 CONTINUATION: containing a: 3 etc…
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | grpcio | all versions | 1.53.2pip install --upgrade 'grpcio==1.53.2' |
| 🐍PyPI | grpcio | ≥ 1.54.0&&< 1.54.3 | 1.54.3pip install --upgrade 'grpcio==1.54.3' |
| 🐍PyPI | grpcio | ≥ 1.55.0&&< 1.55.2 | 1.55.2pip install --upgrade 'grpcio==1.55.2' |
| 🐍PyPI | grpcio | ≥ 1.56.0&&< 1.56.2 | 1.56.2pip install --upgrade 'grpcio==1.56.2' |
| 💎RubyGems | grpc | all versions | 1.53.2bundle update grpc --conservative |
| 💎RubyGems | grpc | ≥ 1.54.0&&< 1.54.3 | 1.54.3bundle update grpc --conservative |
Affected Products
grpcgrpcDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for grpcio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update grpcio to 1.53.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-496j-2rq6-j6cc is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is specific to C++ implementations of gRPC prior to the 1.57 release. The gRPC library was packaged with Openshift via the Kuryr component. However, Kuryr was never configured to run code using the gRPC library and has since been removed.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-496j-2rq6-j6cc (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 9 | rhc-worker-playbook-0:0.1.10-1.el9_5 | RHSA-2024:10761 |
Frequently Asked Questions
Is GHSA-496j-2rq6-j6cc in your dependencies?
Find it across PyPI, RubyGems, including transitive dependencies.