CVE-2016-4556 Use after free in n/a

What is CVE-2016-4556?

CVE-2016-4556 is a high-severity use after free vulnerability in Canonical Ubuntu Linux, published on 10 May 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Double free vulnerability in Esi.cc in Squid 3.x before 3.5.18 and 4.x before 4.0.10 allows remote servers to cause a denial of service (crash) via a crafted Edge Side Includes (ESI) response.

Which versions are affected by CVE-2016-4556?

It affects 3 products.

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

How do I fix CVE-2016-4556?

Upgrade to a fixed version.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2016-4556 being exploited?

There is no known exploitation of CVE-2016-4556 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 GHSA-2xhq-835p-4pg5, UBUNTU-CVE-2016-4556.