Medium severity4.0NVD Advisory· Published Apr 12, 2026· Updated Apr 17, 2026
CVE-2026-40394
CVE-2026-40394
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
14cpe:2.3:a:varnish-software:varnish_enterprise:*:*:*:*:*:*:*:*+ 11 more
- cpe:2.3:a:varnish-software:varnish_enterprise:*:*:*:*:*:*:*:*range: <=6.0.15
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r1:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r10:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r2:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r3:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r4:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r5:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r6:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r7:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r8:*:*:*:*:*:*
- cpe:2.3:a:varnish-software:varnish_enterprise:6.0.16:r9:*:*:*:*:*:*
- (no CPE)range: <6.0.16r11
- cpe:2.3:a:vinyl-cache:vinyl_cache:9.0.0:*:*:*:*:*:*:*
- Range: >=9, <9.0.1
Patches
Vulnerability mechanics
References
1- docs.varnish-software.com/security/VEV00002/nvdVendor Advisory
News mentions
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