CVE-2020-25097
Description
A flaw was found in squid. Due to improper validation while parsing the request URI, squid is vulnerable to HTTP request smuggling. This issue could allow a trusted client to perform an HTTP request smuggling attack and access services otherwise forbidden by squid. The highest threat from this vulnerability is to data confidentiality.
Statement
This flaw is not tied to a specific proxy type (e.g., forward or reverse) and has been rated as having a security impact of Important. This flaw affects the versions of Squid as shipped with Red Hat Enterprise Linux 7 and 8, and is not currently planned to be addressed in future updates of Red Hat Enterprise Linux 6. Red Hat Enterprise Linux 6 is now in Extended Life Phase of the support and maintenance life cycle. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Mitigation
This flaw can be mitigated by setting the `uri_whitespace` directive in squid.conf to either:
uri_whitespace denyor
uri_whitespace encode
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.6 | 8.6 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Red Hat CVSS v3 Score Explanation
The vulnerable component is the Squid proxy itself while the impacted component is any user who is unknowingly attacked as a result of the HTTP request smuggling attack.
Understanding the Weakness (CWE)
Integrity,Non-Repudiation,Access Control
Technical Impact: Unexpected State; Hide Activities; Bypass Protection Mechanism
An attacker could create HTTP messages to exploit a number of weaknesses including 1) the message can trick the web server to associate a URL with another URL's webpage and caching the contents of the webpage (web cache poisoning attack), 2) the message can be structured to bypass the firewall protection mechanisms and gain unauthorized access to a web application, and 3) the message can invoke a script or a page that returns client credentials (similar to a Cross Site Scripting attack).
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