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CVE-2026-40394

Quick assessment

Affected
varnish-software Varnish Cache
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Varnish Cache和Varnish Enterprise都是Varnish公司的产品。Varnish Cache是一套反向网站缓存服务器。Varnish Enterprise是一款高性能的缓存软件。用于处理高流量、优化业务。 Varnish Cache 9.0.1之前版本和Varnish Enterprise 6.0.16r11之前版本存在安全漏洞，该漏洞源于特定数量的预取数据可能导致工作空间溢出拒绝服务。

CVSS 4.0 · Medium EPSS 0.40% · P33

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-40394

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
控制流实现总是不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Varnish Cache和Varnish Enterprise 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Varnish Cache和Varnish Enterprise都是Varnish公司的产品。Varnish Cache是一套反向网站缓存服务器。Varnish Enterprise是一款高性能的缓存软件。用于处理高流量、优化业务。 Varnish Cache 9.0.1之前版本和Varnish Enterprise 6.0.16r11之前版本存在安全漏洞，该漏洞源于特定数量的预取数据可能导致工作空间溢出拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
varnish-software Varnish Cache 9.0.0 ~ 9.0.1 -

II. Public POCs for CVE-2026-40394

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III. Intelligence Information for CVE-2026-40394

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Same Patch Batch · varnish-software · 2026-04-12 · 3 CVEs total

CVE-2026-40396 4.0 MEDIUM Varnish Cache 安全漏洞
CVE-2026-40395 4.0 MEDIUM Varnish Enterprise 安全漏洞

IV. Related Vulnerabilities

Same product: Varnish Cache
Same vendor: varnish-software
Same weakness: CWE-670

V. Comments for CVE-2026-40394

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