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h2 servers vulnerable to degradation of service with CONTINUATION Flood

Moderate severity GitHub Reviewed Published Apr 5, 2024 to the GitHub Advisory Database • Updated Apr 5, 2024

Package

cargo h2 (Rust)

Affected versions

< 0.3.26
>= 0.4.0, < 0.4.4

Patched versions

0.3.26
0.4.4

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.

References

Published to the GitHub Advisory Database Apr 5, 2024
Reviewed Apr 5, 2024
Last updated Apr 5, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Weaknesses

CVE ID

No known CVE

GHSA ID

GHSA-q6cp-qfwq-4gcv

Source code

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