CVE catalog
CVE-2021-28543
varnish-modules: CVE-2021-28543
- Severity
- Low
- Source
- [NVD] · [CVE record]
- EPSS
- 1.49% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | varnish-modules | trixie | 0.25.0-2 | not affected |
| Debian | varnish-modules | bookworm | 0.20.0-2 | not affected |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | varnish-modules | source | trixie | Not affected | unimportant | Not reported | Not reported |
| Debian | varnish-modules | source | bookworm | Not affected | unimportant | Not reported | Not reported |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [varnish-modules]Not affected
Details (2)
0.20.0-2· amd64 · bookwormNot affected
dsa · varnish-modules · debian · bookworm
0.20.0-2· arm64 · bookwormNot affected
dsa · varnish-modules · debian · bookworm
Observed: