CVE Tools
Home/Vulnerability/CVE-2026-40394

CVE-2026-40394

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 se...

Published: Apr 12, 2026Updated: Apr 12, 2026 Sources: CVE List NVD
NVD MITRE
4.0CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:CC:NI:NA:L
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:LAvailability
Low

Weaknesses

CWE-670

Affected Products

Varnish Cache
varnish-software

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

https://docs.varnish-software.com/security/VEV00002/
docs.varnish-software.com

Timeline

Published
Apr 12, 2026
Last Updated
Apr 12, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-40394 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
AI-powered analysis
Plain-language impact assessment and exploitation scenario
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows