SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2020-15811

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.

MEDIUM 6.5EPSS 4.23%

Does this matter?

Lower severity and a low EPSS score (4.23%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1
6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
EPSS
4.23% probability · 90th percentile
CISA KEV
Not listed
Weakness
CWE-697
Affected
squid-cache/squid · canonical/ubuntu linux · debian/debian linux · fedoraproject/fedora · opensuse/leap
Source
cve@mitre.org

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.