First published: Wed Apr 15 2020(Updated: )
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.
Credit: cve@mitre.org cve@mitre.org
Affected Software | Affected Version | How to fix |
---|---|---|
Squid-Cache Squid | >=3.0<=3.5.28 | |
Squid-Cache Squid | >=4.0<=4.7 | |
Squid-Cache Squid | >=5.0<=5.0.1 | |
Canonical Ubuntu Linux | =16.04 | |
Canonical Ubuntu Linux | =18.04 | |
Canonical Ubuntu Linux | =19.10 | |
Canonical Ubuntu Linux | =20.04 | |
Debian Debian Linux | =9.0 | |
Debian Debian Linux | =10.0 | |
openSUSE Leap | =15.1 | |
ubuntu/squid | <4.8-1ubuntu2.3 | 4.8-1ubuntu2.3 |
ubuntu/squid | <4.10-1ubuntu1.1 | 4.10-1ubuntu1.1 |
ubuntu/squid | <4.10-1ubuntu2 | 4.10-1ubuntu2 |
ubuntu/squid | <4.10-1ubuntu2 | 4.10-1ubuntu2 |
ubuntu/squid | <4.11 | 4.11 |
ubuntu/squid3 | <3.5.27-1ubuntu1.6 | 3.5.27-1ubuntu1.6 |
ubuntu/squid3 | <3.5.12-1ubuntu7.11 | 3.5.12-1ubuntu7.11 |
debian/squid | 4.6-1+deb10u7 4.6-1+deb10u10 4.13-10+deb11u2 4.13-10+deb11u3 5.7-2 5.7-2+deb12u1 6.6-1 6.9-1 |
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CVE-2019-12521 is a vulnerability discovered in Squid through 4.7 that allows remote attackers to cause a denial of service (daemon crash) or possibly execute arbitrary code.
The severity of CVE-2019-12521 is medium, with a CVSS score of 5.9.
CVE-2019-12521 affects Squid versions up to 4.7.
To fix CVE-2019-12521, it is recommended to upgrade Squid to version 4.8 or later.
More information about CVE-2019-12521 can be found at the following references: [Link 1](https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt), [Link 2](http://www.openwall.com/lists/oss-security/2020/04/23/1), [Link 3](https://www.debian.org/security/2020/dsa-4682).