CVE-2020-15811 Information
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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 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Reference
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00012.html http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00017.html https://github.com/squid-cache/squid/security/advisories/GHSA-c7p8-xqhm-49wv https://lists.debian.org/debian-lts-announce/2020/10/msg00005.html https://lists.fedoraproject.org/archives/list/[email protected]/message/BE6FKUN7IGTIR2MEEMWYDT7N5EJJLZI2/ https://lists.fedoraproject.org/archives/list/[email protected]/message/BMTFLVB7GLRF2CKGFPZ4G4R5DIIPHWI3/ https://lists.fedoraproject.org/archives/list/[email protected]/message/HJJDI7JQFGQLVNCKMVY64LAFMKERAOK7/ https://usn.ubuntu.com/4477-1/ https://usn.ubuntu.com/4551-1/ https://www.debian.org/security/2020/dsa-4751
Attack Complexity
LOW
Privileges Required
LOW
User Interaction Required
LOW
Scope
NONE
Confidentiality Impact
UNCHANGED
Integrity Impact
NONE
Availability Impact
HIGH
Base Score
NONE
Base Severity
6.5