What is CVE-2026-40395?

CVE-2026-40395 is a medium-severity vulnerability in Varnish-software Varnish Enterprise, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 4.0/10. Published 2026-04-12.

How severe is CVE-2026-40395?

Medium severity. CVSS v3 base score is 4.0 out of 10.

Resource exhaustion in Varnish-software Varnish Enterprise

CVE-2026-40395

Varnish Enterprise before 6.0.16r12 allows a "workspace overflow" denial of service (daemon panic) for shared VCL. The headerplus.write_req0() function from vmod_headerplus updates the underlying req0, which is normally the original read-o…

EPSS: 0.001 (19.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L.

Affected products

Varnish-software Varnish Enterprise — versions 6.0.9r5

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

docs.varnish-software.com/security/VEV00003/

Frequently asked questions

What is CVE-2026-40395?: CVE-2026-40395 is a medium-severity vulnerability in Varnish-software Varnish Enterprise, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 4.0/10. Published 2026-04-12.
How severe is CVE-2026-40395?: Medium severity. CVSS v3 base score is 4.0 out of 10.