VulnSocial

CVE-2026-40394Disclosure(varnish-software / varnish_enterprise)

LOWCVSS 7.5 · HIGH

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD 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.

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0.5/ 10 priority

Sources & remediation

Vendor / third-party advisories
Weakness type (CWE)
CWE-670

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • varnish_enterprise
  • vinyl_cache

Threat summary

  • 2 mentions across 2 observed days
  • Momentum state: stable

What's happening

  • Technical details provided in 2 signals
  • Disclosure: 2 classified signals
  • Peaked 1d ago at 1 mentions (2026-04-12); latest day: 1
  • 2 total mentions across 2 days

Affected systems

Vendors
varnish-softwarevinyl-cache
Products
varnish_enterprisevinyl_cache

2 versions affected across 2 products

Deep dive

Activity timeline2 mentions / 2d
00111Mentions · 2026-04-12: 1Mentions · 2026-04-13: 1Technical Details · 2026-04-12: 1Technical Details · 2026-04-13: 104-1204-13
Signal classification1 categories
Disclosure
2100.0%
Referenced assets3 URLs
Full discourse2 posts
  • CVE@CVEnew
    Disclosure

    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 … https://www.cve.org/CVERecord?id=CVE-2026-40394

    Post summary

    A denial‑of‑service flaw in Varnish Cache versions prior to 9.0.1 and Varnish Enterprise before 6.0.16r11 has been disclosed as CVE‑2026‑40394, detailing a workspace overflow that triggers a daemon panic.

    00000101
    57.1K followersView on X
  • Vulmon Vulnerability Feed@VulmonFeeds
    Disclosure

    CVE-2026-40394 Workspace Overflow Denial of Service in Varnish Cache Before 9.0.1 https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-40394 Vulnerability Notification: https://alerts.vulmon.com/?utm_source=twitter&utm_medium=social&utm_campaign=2102281&utm_content=3

    Post summary

    This tweet announces a Denial of Service vulnerability (CVE‑2026‑40394) in Varnish Cache versions prior to 9.0.1, providing links to vulnerability details but no PoC, exploit, or patch information.

    0000054
    4.0K followersView on X
CPE platform detail12 entries

12 of 12 entries

PartVendorProductVersionTarget SWTarget HW
Appvarnish-softwarevarnish_enterprise---
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvarnish-softwarevarnish_enterprise6.0.16--
Appvinyl-cachevinyl_cache9.0.0--

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