{"id":"UBUNTU-CVE-2026-40394","details":"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.","modified":"2026-05-20T16:25:39.959227707Z","published":"2026-04-12T20:16:00Z","upstream":["CVE-2026-40394"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-40394"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-40394"},{"type":"REPORT","url":"https://docs.varnish-software.com/security/VEV00002/"}],"affected":[{"package":{"name":"varnish","ecosystem":"Ubuntu:14.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.4-1ubuntu1","3.0.4-1ubuntu2","3.0.5-1ubuntu2","3.0.5-2","3.0.5-2ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi1","binary_version":"3.0.5-2ubuntu0.1"},{"binary_version":"3.0.5-2ubuntu0.1","binary_name":"varnish"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.0.3-1","4.1.0-1","4.1.0-2","4.1.1-1","4.1.1-1ubuntu0.2","4.1.1-1ubuntu0.2+esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.1.1-1ubuntu0.2+esm1","binary_name":"libvarnishapi1"},{"binary_name":"varnish","binary_version":"4.1.1-1ubuntu0.2+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.0.0-7.1","5.2.1-1","5.2.1-1ubuntu0.1","5.2.1-1ubuntu0.1+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi1","binary_version":"5.2.1-1ubuntu0.1+esm1"},{"binary_version":"5.2.1-1ubuntu0.1+esm1","binary_name":"varnish"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.1.1-1","6.2.1-2","6.2.1-2ubuntu0.1~esm1","6.2.1-2ubuntu0.1~esm2","6.2.1-2ubuntu0.1","6.2.1-2ubuntu0.2","6.2.1-2ubuntu0.2+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi2","binary_version":"6.2.1-2ubuntu0.2+esm1"},{"binary_version":"6.2.1-2ubuntu0.2+esm1","binary_name":"varnish"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.5.2-1","6.6.1-1","6.6.1-1ubuntu0.2","6.6.1-1ubuntu0.2+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi2","binary_version":"6.6.1-1ubuntu0.2+esm1"},{"binary_name":"varnish","binary_version":"6.6.1-1ubuntu0.2+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.1.1-1.1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi3","binary_version":"7.1.1-1.1ubuntu1"},{"binary_version":"7.1.1-1.1ubuntu1","binary_name":"varnish"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.7.0-1","7.7.0-2","7.7.0-3","7.7.3-1"],"ecosystem_specific":{"binaries":[{"binary_version":"7.7.3-1","binary_name":"libvarnishapi3"},{"binary_name":"varnish","binary_version":"7.7.3-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}},{"package":{"name":"varnish","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/varnish?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.7.3-1","7.7.3-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libvarnishapi3","binary_version":"7.7.3-1build1"},{"binary_version":"7.7.3-1build1","binary_name":"varnish"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40394.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}