CVE-2026-93894: Varnish-Software Varnish Cache

Low severity, CVSS 2.3. EPSS: 0.4% chance of exploitation in the next 30 days.

In Vinyl Cache before 9.0,2, workspace buffer overflow vulnerability was found in the .upper() and .lower() string type methods of VCL. This can be used as a remote denial of service (DoS) vector to make the child process segfault or assert, and then restart. Effectively exploiting this vulnerability requires prior knowledge about the VCL in use and the ability to craft a request that contains a string that is long enough to fill the remaining workspace at the call site while staying under the different request size limits (http_req_size, http_req_hdr_len, etc.).

Affected products

• Varnish-Software Varnish Cache: from 9.0.0, before 9.0.4 (fixed in 9.0.4); from 6.3.0, up to and including 8.0.2
• Vinyl-Cache Vinyl Cache: before 9.0.2 (fixed in 9.0.2)

Published 2026-09-18. Last modified 2026-09-22.