CVE-2026-40394
Summary
| CVE | CVE-2026-40394 |
|---|---|
| State | PUBLISHED |
| Assigner | mitre |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-12 20:16:17 UTC |
| Updated | 2026-04-17 14:35:23 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.000550000 probability, percentile 0.173000000 (date 2026-04-21)
Problem Types: CWE-670 | CWE-670 CWE-670 Always-Incorrect Control Flow Implementation
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | [email protected] | Secondary | 4 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L |
| 3.1 | CNA | CVSS | 4 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r1 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r10 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r2 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r3 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r4 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r5 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r6 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r7 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r8 | All | All |
| Application | Varnish-software | Varnish Enterprise | 6.0.16 | r9 | All | All |
| Application | Varnish-software | Varnish Enterprise | All | All | All | All |
| Application | Vinyl-cache | Vinyl Cache | 9.0.0 | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Varnish-software | Varnish Cache | affected 9.0.0 9.0.1 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| docs.varnish-software.com/security/VEV00002 | [email protected] | docs.varnish-software.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.