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GHSA-4vr9-8cjf-vf9c

MediumCVSS 6.8 / 10
Published Oct 12, 2021·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

Description

Impact

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.

Patches

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

Workarounds

none

References

https://github.com/http-rs/async-h1/releases/tag/v2.3.0

For more information

If you have any questions or comments about this advisory:

Risk Scores
Base Score
6.8

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the integrity of the data.

Threat Intelligence
6.2

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
1.01%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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