CVE-2021-28543 describes a denial-of-service vulnerability in Varnish varnish-modules before version 0.17.1, affecting configurations where both Varnish Cache and varnish-modules are installed. Remote attackers can trigger a daemon restart through specific header manipulation functions (header.append() and header.copy()) in Varnish Configuration Language (VCL) files. This vulnerability has a CVSS score of 7.5 (HIGH), indicating a network-based attack with low complexity and high impact on availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 0.17.1CPE matchmatch criteria | cpe:2.3:a:varnish-cache:varnish-modules:*:*:*:*:*:*:*:* | ||
< 0.17.1CPE matchmatch criteria | cpe:2.3:a:varnish-cache:varnish-modules_klarlack:*:*:*:*:*:*:*:* | ||
34CPE matchmatch criteria | cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L
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The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.
varnish-modules: NULL pointer dereference in Varnish Cache via header.append() and header.copy() functions
Mar 16, 2021Varnish 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.
Mar 9, 2021