Cache poisoning in Squid

Published: 2020-03-20 | Updated: 2020-05-11
Risk Low
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2019-18860
Exploitation vector Network
Public exploit N/A
Vulnerable software
Server applications / IDS/IPS systems, Firewalls and proxy servers


Security Advisory

This security advisory describes one low risk vulnerability.

1) Improper Neutralization of Special Elements in Output Used by a Downstream Component

Risk: Low

CVSSv3: 3.8 [CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-18860

CWE-ID: CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Exploit availability: No


The vulnerability allows a remote attacker to perform cache poisoning attack.

The vulnerability exists due to improper input validation of HTML code within the hostname parameter in cachemgr.cgi. A remote attacker can send a specially crated HTTP request and poison the cache.


Install updates from vendor's website.

Vulnerable software versions

Squid: 4.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.0.6, 4.0.7, 4.0.8, 4.0.9, 4.0.10, 4.0.11, 4.0.12, 4.0.13, 4.0.14, 4.0.15, 4.0.16, 4.0.17, 4.0.18, 4.0.19, 4.0.20, 4.0.21, 4.0.22, 4.0.23, 4.0.24, 4.0.25, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8

CPE External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.