CVE-2026-40394

highpriority · track · 30EPSS 0.002 · 15 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.24% (15th) EPSS

CVSS 7.5 · high

Is it mine?

6 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4–7.5

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · ENISA EU

v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · cve@mitre.org USexploitability 2.2 · impact 1.4

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-670US

affected products (6)

Products and version ranges known to be affected.

Open Source Varnish HTTP Cache <9.0.1all versionscert_bundDE
Open Source Varnish HTTP Cache< 9.0.1cert_bundDE
varnish-software Varnish Cache9.0.0 → 9.0.1enisa_euvdEU
varnish-software varnish enterprise≤ 6.0.15nvdUScpe:2.3:a:varnish-software:varnish_enterprise:*:*:*:*:*:*:*:*
varnish-software varnish enterprise= 6.0.16nvdUScpe:2.3:a:varnish-software:varnish_enterprise:*:*:*:*:*:*:*:*
vinyl-cache vinyl cache= 9.0.0nvdUScpe:2.3:a:vinyl-cache:vinyl_cache:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-1061Varnish HTTP Cache: Mehrere Schwachstellen ermöglichen Denial of ServiceDeutsch2026-04-12csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Varnish HTTP Cache ausnutzen, um einen Denial of Service Angriff durchzuführen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd NVD CVE.org MITRE

published 2026-04-12modified 2026-10-26

references (4)

External citations — patches, advisories, analysis.

scry

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