h2 servers vulnerable to degradation of service with CONTINUATION Flood
Priority LOW 38CWE-400Published · Updated
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
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- Attack complexity
- —
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- —
- Fix status
- Fixed
No CVSS vector from any source. Fix status from GitHub. Impact type from CWE-400.
Summary
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.
Why it matters now
Fix Fixed h2 (crates.io): 0.3.26, 0.4.4
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | h2 (crates.io) | before 0.3.26 | 0.3.26 | Patch available | GHSA-q6cp-qfwq-4gcv |
| — | h2 (crates.io) | 0.4.0 to before 0.4.4 | 0.4.4 | Patch available | GHSA-q6cp-qfwq-4gcv |
- h2 (crates.io) Vendor— Affected before 0.3.26 Fixed in 0.3.26 Patch available GHSA-q6cp-qfwq-4gcv
- h2 (crates.io) Vendor— Affected 0.4.0 to before 0.4.4 Fixed in 0.4.4 Patch available GHSA-q6cp-qfwq-4gcv
Remediation
- Fix · GHSA-q6cp-qfwq-4gcv h2 (crates.io) Fixed in 0.3.26 Advisory →
- Fix · GHSA-q6cp-qfwq-4gcv h2 (crates.io) Fixed in 0.4.4 Advisory →
Timeline
- 2026-10-03 Threatist record created from GHSA-q6cp-qfwq-4gcv
References
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences