GHSA-q6cp-qfwq-4gcv — h2
MEDIUMGHSA-q6cp-qfwq-4gcv is a medium-severity (CVSS 5.3) vulnerability in h2. A fix is available for h2 — see the affected versions and patch details below.
h2 servers vulnerable to degradation of service with CONTINUATION Flood
Real-World Exposure
h2🦀h2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
An attacker can send a flood of CONTINUATION frames, causing h2 to process them indefinitely. This results in an increase in CPU usage.
Tokio task budget helps prevent this from a complete denial-of-service, as the server can still respond to legitimate requests, albeit with increased latency.
More details at https://seanmonstar.com/blog/hyper-http2-continuation-flood/.
Patches available for 0.4.x and 0.3.x versions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | h2 | all versions | 0.3.26cargo update -p h2 --precise 0.3.26 |
| 🦀crates.io | h2 | ≥ 0.4.0&&< 0.4.4 | 0.4.4cargo update -p h2 --precise 0.4.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for h2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update h2 to 0.3.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q6cp-qfwq-4gcv 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-q6cp-qfwq-4gcv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-q6cp-qfwq-4gcv. 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-q6cp-qfwq-4gcv in your dependencies?
O3 Security finds GHSA-q6cp-qfwq-4gcv across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.