CVE-2026-40394
4.0 · MEDIUMOverview
CVE-2026-40394 is a medium-severity vulnerability affecting varnish-software varnish_enterprise. It was published on April 12, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from varnish-software. Update varnish_enterprise to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| varnish-software | varnish_enterprise | 0 | Affected |
Frequently Asked Questions
What is CVE-2026-40394?
CVE-2026-40394 is a medium-severity vulnerability affecting varnish-software varnish_enterprise. It was published on April 12, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).
How severe is CVE-2026-40394?
This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-40394?
Check the references section for vendor advisories and patches from varnish-software. Update varnish_enterprise to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-40394?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-40394 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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