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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 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 p
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:c5bdf683af6683a5efbb2c4ae072a48a4943001058d81c76f843ee720aed1d65
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0

Affected products and versions

1 source assertion
{"defaultStatus":"unaffected","product":"Varnish Cache","vendor":"varnish-software","versions":[{"lessThan":"9.0.1","status":"affected","version":"9.0.0","versionType":"semver"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:aff63adac3739b19d120b702be68ff6fa46fbf1f43a572667321c4ed0359bcca · sha256:c53e610e27286058… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:aff63adac3739b19d120b702be68ff6fa46fbf1f43a572667321c4ed0359bcca · sha256:c53e610e27286058… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion
{"cweId":"CWE-670","description":"CWE-670 Always-Incorrect Control Flow Implementation","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:aff63adac3739b19d120b702be68ff6fa46fbf1f43a572667321c4ed0359bcca · sha256:c53e610e27286058… · /containers/cna/problemTypes/0/descriptions/0

Source references

1 source assertion
{"url":"https://docs.varnish-software.com/security/VEV00002/"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:aff63adac3739b19d120b702be68ff6fa46fbf1f43a572667321c4ed0359bcca · sha256:c53e610e27286058… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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