CVE-2021-28543
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.
How to fix
- varnish-cache varnish-modules0.17.1 or later
- varnish-cache varnish-modules_klarlack0.17.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| varnish-cache varnish-modules | v < 0.17.1 | 0.17.1 |
| varnish-cache varnish-modules_klarlack | v < 0.17.1 | 0.17.1 |
| fedoraproject fedora | 34 | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.