CVE-2021-36740

Publication date 14 July 2021

Last updated 25 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.5 · Medium

Score breakdown

Description

Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. This affects Varnish Enterprise 6.0.x before 6.0.8r3, and Varnish Cache 5.x and 6.x before 6.5.2, 6.6.x before 6.6.1, and 6.0 LTS before 6.0.8.

Read the notes from the security team

Status

Package Ubuntu Release Status
varnish 22.04 LTS jammy
Not affected
21.10 impish
Fixed 6.5.2-1
21.04 hirsute Ignored end of life
20.10 groovy Ignored end of life
20.04 LTS focal
Fixed 6.2.1-2ubuntu0.1
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected

Notes

ebarretto

According to Debian: (HTTP/2 support is marked experimental in 5.0 and enabling is not recommended, code is quite different)

Severity score breakdown

Parameter Value
Base score 6.5 · Medium
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality Low
Integrity impact Low
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References

Related Ubuntu Security Notices (USN)

    • USN-5474-1
    • Varnish Cache vulnerabilities
    • 8 June 2022

Other references