CVE-2020-15811

Description

An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP Request Splitting attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This allows any client, including browser scripts, to bypass local security and poison the browser cache and any downstream caches with content from an arbitrary source. Squid uses a string search instead of parsing the Transfer-Encoding header to find chunked encoding. This allows an attacker to hide a second request inside Transfer-Encoding: it is interpreted by Squid as chunked and split out into a second request delivered upstream. Squid will then deliver two distinct responses to the client, corrupting any downstream caches.

How to fix CVE-2020-15811

To remediate CVE-2020-15811, upgrade the affected package to a fixed version below.

• —upgrade to 4.13-r0 or later
• —upgrade to 4.13-1 or later

Is CVE-2020-15811 being exploited?

Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 4.13-r0
• from 0, < 4.13-1

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2020-15811
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2020-15811