CVE-2019-12521 Memory corruption in n/a

What is CVE-2019-12521?

CVE-2019-12521 is a medium-severity memory corruption vulnerability in Canonical Ubuntu Linux, published on 15 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.

Weakness: CWE-787, CWE-193

Which versions are affected by CVE-2019-12521?

It affects 4 products.

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

How do I fix CVE-2019-12521?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2019-12521 being exploited?

There is no known exploitation of CVE-2019-12521 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 ALPINE-CVE-2019-12521, DEBIAN-CVE-2019-12521, GHSA-7mv4-9v7r-5gq3, OESA-2022-1851, UBUNTU-CVE-2019-12521.