CVE-2019-12520

squid: Improper input validation in request allows for proxy manipulation

Published Apr 15, 2020 CVSS 3.1 · 7.5 High EPSS 3.9% KEV · Not listed
Description
An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-2278-1 squid3 security update
Debian DSA Debian DSA DSA-4682-1 squid security update
EUVD EUVD EUVD-2019-4115 An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.
Ubuntu USN Ubuntu USN USN-4446-1 Squid vulnerabilities
History
Type Values Removed Values Added
Metrics epss

{'score': 0.06184}

epss

{'score': 0.06343}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Aug 4, 2024, 11:24 PM
Reserved
Jun 2, 2019, 12:00 AM
Status
Modified
Published
Apr 15, 2020, 8:15 PM
Modified
Jun 17, 2026, 2:14 AM
Severity
Moderate
Public date
Apr 24, 2020, 12:00 AM