AUGUST 4, 2026
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Case File

CVE-2021-28543

MEDIUM · CVSS 4 EPSS 1.49%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-03-16 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 4.0. It may be remotely exploitable. It may lead to a denial-of-service condition.

CVE
CVE-2021-28543
Severity
MEDIUM
CVSS
4
EPSS
1.49%

Original NVD Description

Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers.

Related CVEs

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