# CVE-2026-50052: Vinyl Cache and Varnish Cache Request Smuggling in HTTP/2 parsing

Source: https://junglewise.ai/threats/cve-2026-50052-vinyl-cache-and-varnish-cache-request-smuggling-in-http-2-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-03. Updated: 2026-06-03  
License: CC BY 4.0 with a link back

CVE-2026-50052 · Severity: info · CVSS 2.3 · Published 2026-06-03

Vinyl Cache and Varnish Cache are high-performance web accelerators used to speed up websites by caching content. A security flaw in how these systems process modern web traffic (HTTP/2) could allow an attacker to 'smuggle' hidden requests to backend servers. This could lead to unauthorized access to data, the serving of incorrect or malicious content to other users (cache poisoning), or the bypassing of security controls.

## Quick answers

**Is CVE-2026-50052 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-50052 being exploited in the wild.

**How severe is CVE-2026-50052?** Informational severity, with a CVSS score of 2.3, published 3 June 2026.

**Which products and versions are affected?** Vinyl Cache Project Vinyl Cache 9.0.0; Varnish Software Varnish Cache 7.6.0 to 8.0.1, 6.0.14 to 6.0.17, and versions up to 9.0.2.

**Is there a fix for CVE-2026-50052?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-50052 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-50052?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in the HTTP/2 request parsing logic of Vinyl Cache and Varnish Cache, classified as a Request Smuggling (CWE-444) flaw. By sending specially crafted HTTP/2 requests, an attacker can cause a desynchronization between the cache proxy and the backend server. This allows the attacker to 'smuggle' a second request inside the first, which the backend interprets as a separate, legitimate request. This can be leveraged for cache poisoning, bypassing authentication, or information disclosure. The vulnerability is only exploitable if HTTP/2 support is explicitly enabled (it is disabled by default). Patches are available in Vinyl Cache 9.0.1 and Varnish Cache 9.0.3, 8.0.2, and 6.0.18.

## Affected products

- Vinyl Cache Project Vinyl Cache 9.0.0
- Varnish Software Varnish Cache 7.6.0 to 8.0.1, 6.0.14 to 6.0.17, and versions up to 9.0.2

## Timeline

- 2026-05-18: disclosed: Initial publication of VSV00019 and release of patches.
- 2026-05-28: other: Advisory last updated.
- 2026-06-03: advisory: CVE-2026-50052 published to NVD.

## References

- [https://vinyl-cache.org/security/VSV00019.html](https://vinyl-cache.org/security/VSV00019.html)