CVE-2026-40394
HIGH
MEDIUM
Priority: 0.02
BB Relevance:
75/100
Published: 2026-04-12
Modified: 2026-10-26
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Unchanged
C:
None
I:
None
A:
High
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.
Weakness Classification (1)
Affected Software (12)
| Vendor | Product | Version |
|---|---|---|
| varnish-software | varnish_enterprise | < 6.0.15 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| varnish-software | varnish_enterprise | 6.0.16 |
| vinyl-cache | vinyl_cache | 9.0.0 |
References & Advisories (1)
Vendor Advisory