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Security Advisories: GSA_kwCzR0hTQS00dnI5LThjamYtdmY5Y80Waw

Async-h1 request smuggling possible with long unread bodies


This vulnerability affects any webserver that uses async-h1 behind a reverse proxy, including all such Tide applications.

If the server does not read the body of a request which is longer than some buffer length, async-h1 will attempt to read a subsequent request from the body content starting at that offset into the body.

One way to exploit this vulnerability would be for an adversary to craft a request such that the body contains a request that would not be noticed by a reverse proxy, allowing it to forge forwarded/x-forwarded headers. If an application trusted the authenticity of these headers, it could be misled by the smuggled request.

Another potential concern with this vulnerability is that if a reverse proxy is sending multiple http clients' requests along the same keep-alive connection, it would be possible for the smuggled request to specify a long content and capture another user's request in its body. This content could be captured in a post request to an endpoint that allows the content to be subsequently retrieved by the adversary.


This has been addressed in async-h1 2.3.0 and previous versions have been yanked.




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Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: over 2 years ago
Updated: about 1 year ago

CVSS Score: 6.8
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

Identifiers: GHSA-4vr9-8cjf-vf9c, CVE-2020-26281
References: Repository:
Blast Radius: 18.7

Affected Packages

Dependent packages: 34
Dependent repositories: 560
Downloads: 3,019,782 total
Affected Version Ranges: < 2.3.0
Fixed in: 2.3.0
All affected versions: 0.0.0, 1.0.0, 1.0.1, 1.0.2, 1.1.0, 1.1.1, 1.1.2, 2.0.0, 2.0.1, 2.0.2, 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.2.0, 2.2.1
All unaffected versions: 2.3.0, 2.3.1, 2.3.2, 2.3.3, 2.3.4