Varnish · Vinyl Cache · CVE-2026-50052
**Name of the Vulnerable Software and Affected Versions**
Vinyl Cache versions prior to 9.0.1
Varnish Cache versions prior to 9.0.3
**Description**
A deficiency in HTTP/2 request parsing allows for backend request desync attacks, also known as request smuggling. This occurs when the frontend and backend servers disagree on where a request ends, allowing an attacker to "smuggle" a request. This can lead to cache poisoning, authentication bypass, information disclosure, and data manipulation. The issue is only present if HTTP/2 support is enabled by configuring the `feature` parameter to include `+http2`. By default, this support is disabled.
**Recommendations**
Update Vinyl Cache to version 9.0.1 or later.
Update Varnish Cache to version 9.0.3 or later.
As a temporary mitigation, ensure that HTTP/2 support is disabled by removing `+http2` from the `feature` parameter.