🛡️ CVE-2026-40394
🟡 CVSS 4.0 — Medium ✅ No Known Exploit CWE-670 NVD
4.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Varnish Cache 9 before 9.0.1 and Varnish Enterprise before 6.0.16r11 allows a "workspace overflow" denial of service (daemon panic) for certain amounts of prefetched data. The setup of an HTTP/2 session starts with a speculative HTTP/1 transport, and upon upgrading to h2 the HTTP/1 request is repurposed as stream zero. During the upgrade, a buffer allocation is made to reserve space to send frames to the client. This allocation would split the original workspace, and depending on the amount of prefetched data, the next fetch could perform a pipelining operation that would run out of workspace.

Details

Severity MEDIUM
CVSS Score 4.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
CWE CWE-670
Public Exploit ✅ No
Source NVD
Published 2026-04-12
Updated 2026-06-02
Modified 2026-04-17
Fix URL N/A

Affected Packages

Software From version Fixed in
varnish-enterprise — —
vinyl-cache — —

Similar Threats

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