CVE-2020-11653 Denial of service in n/a

What is CVE-2020-11653?

CVE-2020-11653 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 8 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in Varnish Cache before 6.0.6 LTS, 6.1.x and 6.2.x before 6.2.3, and 6.3.x before 6.3.2. It occurs when communication with a TLS termination proxy uses PROXY version 2. There can be an assertion failure and daemon restart, which causes a performance loss.

Weakness: CWE-617

Which versions are affected by CVE-2020-11653?

It affects 5 products.

Products include Debian Debian Linux, Opensuse Backports Sle, Opensuse Leap, Varnish-Cache Varnish Cache, Varnish-Software Varnish Cache.

How do I fix CVE-2020-11653?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-11653 being exploited?

There is no known exploitation of CVE-2020-11653 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2020-11653, GHSA-jg36-89rw-qgr3, UBUNTU-CVE-2020-11653, USN-5474-2.