NULL pointer dereference in Varnish-Cache Varnish-Modules
CVE-2021-28543
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.
EPSS: 0.015 (71.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L.
Affected products
- Varnish-cache Varnish-modules
- Varnish-cache Varnish-modules_klarlack
- Fedoraproject Fedora — versions 34
- N/a — versions n/a
Weakness classification (CWE)
References
- cve@mitre.org (x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (x_refsource_FEDORA, vendor-advisory)
Frequently asked questions
- What is CVE-2021-28543?
- CVE-2021-28543 is a medium-severity vulnerability in Varnish-Cache Varnish-Modules, classified under NULL Pointer Dereference. CVSS score: 4.0/10. Published 2021-03-16.
- How severe is CVE-2021-28543?
- Medium severity. CVSS v3 base score is 4.0 out of 10.