{"schemaVersion":3,"id":"CVE-2026-40394","aliases":["UBUNTU-CVE-2026-40394","DEBIAN-CVE-2026-40394"],"status":"published","duplicateOf":null,"title":null,"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. 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