Vulnerability · Published Sep 18, 2026 · Assigned by mitre
CVE-2026-93894
Low 2.3
In plain English
A low-severity out-of-bounds write in Varnish Cache from Varnish-Software. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | varnish | no fix listed | DEBIAN-CVE-2026-93894 |
| Debian:13 | varnish | 7.7.0-3+deb13u2 | DEBIAN-CVE-2026-93894 |
| Debian:14 | vinyl-cache | 9.0.1-4.1 | DEBIAN-CVE-2026-93894 |
| Ubuntu:24.04:LTS | varnish | no fix listed | UBUNTU-CVE-2026-93894 |
| Ubuntu:26.04:LTS | varnish | no fix listed | UBUNTU-CVE-2026-93894 |
| Ubuntu:26.10 | varnish | no fix listed | UBUNTU-CVE-2026-93894 |
| Ubuntu:26.10 | vinyl-cache | no fix listed | UBUNTU-CVE-2026-93894 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Vinyl-Cache | Vinyl Cache | 0 – before 9.0.20 – before 90f5bacc14b2404e6cc349ba015f0f73b8515136 |
| Varnish-Software | Varnish Cache | 9.0.0 – before 9.0.40 – before c5078ae575201b05ae8674a90ddb19ffe7f4b4396.3.0 – through 8.0.2 |
Weakness: CWE-787 · Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/AU:N/R:A/V:D/RE:L/U:Clear