CVE-2019-12520 An issue was discovered in Squid through 4.7 and 5.

What is CVE-2019-12520?

CVE-2019-12520 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 15 Apr 2020.

Official 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.

Weakness: CWE-20

Which versions are affected by CVE-2019-12520?

It affects 3 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Squid-Cache Squid.

How do I fix CVE-2019-12520?

Upgrade to a fixed version.

Is CVE-2019-12520 being exploited?

There is no known exploitation of CVE-2019-12520 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2019-12520, GHSA-gx26-q49r-m7g8, UBUNTU-CVE-2019-12520.