CVEvulnerability

CVE-2026-40395

7.5 HIGH Published 2026-04-12 Modified 2026-10-26 Official page ↗
Status
Analyzed
Published
2026-04-12
Last modified
2026-10-26
Assigner
[email protected]
CVSS 3.1 ([email protected])
4.0 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-770

Description

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.

Affected configurations

• varnish-software varnish enterprise (<= 6.0.15) • varnish-software varnish enterprise 6.0.16

Related

Weakness · CWE (1)

  • CWE-770 Allocation of Resources Without Limits or Throttling weakness

References