Allocation of Resources Without Limits or Throttling Affecting varnish-devel package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.24% (15th percentile)

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  • Snyk IDSNYK-CENTOS8-VARNISHDEVEL-16056070
  • published15 Apr 2026
  • disclosed12 Apr 2026

Introduced: 12 Apr 2026

CVE-2026-40395  (opens in a new tab)
CWE-770  (opens in a new tab)

How to fix?

There is no fixed version for Centos:8 varnish-devel.

NVD Description

Note: Versions mentioned in the description apply only to the upstream varnish-devel package and not the varnish-devel package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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-only request from which req is derived (readable and writable from VCL). This is useful in the active VCL, after amending req, to prepare a refined req0 before switching to a different VCL with the return (vcl(<label>)) action. This is for example how the Varnish Controller operates shared VCL deployments. If the amended req contained too many header fields for req0, this would have resulted in a workspace overflow that would in turn trigger a panic and crash the Varnish Enterprise server. This could be used as a Denial of Service attack vector by malicious clients.

CVSS Base Scores

version 3.1