VSV00001 DoS vulnerability

[Olav Groenaas Gjerde]

VSV00001 DoS vulnerability

CVE-<to be assigned, we couldn’t get one under embargo>

Date: 2017-08-02

A wrong if statement in the varnishd source code means that particular invalid requests from the client can trigger an assert.

This causes the varnishd worker process to abort and restart, loosing the cached contents in the process.

An attacker can therefore crash the varnishd worker process on demand and effectively keep it from serving content - a Denial-of-Service attack.

Mitigation is possible from VCL or by updating to a fixed version of Varnish Cache.
Versions affected

    4.0.1 to 4.0.4
    4.1.0 to 4.1.7
    5.0.0
    5.1.0 to 5.1.2

http://varnish-cache.org/security/VSV00001.html