CVE-2026-40394_CVE-2026-40394

4 / 10

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L

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.

Basic Information

ID CVE-2026-40394

Source mitre

Published Apr 12, 2026 at 19:17

Modified Apr 12, 2026 at 19:32

Affected Product

Vendor varnish-software

Product Varnish Cache

Version 9.0.0

Affected Versions varnish-software Varnish Cache 9.0.0

CWE Classification

CWE-670

References

docs.varnish-software.com /security/VEV00002/

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    "published": "2026-04-12T19:17:34.334Z",
    "modified": "2026-04-12T19:32:07.658Z",
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