CVE-2018-1172 Null dereference in The Squid Software Foundation Squid

What is CVE-2018-1172?

CVE-2018-1172 is a medium-severity vulnerability in Squid-Cache Squid, published on 16 May 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

This vulnerability allows remote attackers to deny service on vulnerable installations of The Squid Software Foundation Squid 3.5.27-20180318. Authentication is not required to exploit this vulnerability. The specific flaw exists within ClientRequestContext::sslBumpAccessCheck(). A crafted request can trigger the dereference of a null pointer. An attacker can leverage this vulnerability to create a denial-of-service condition to users of the system. Was ZDI-CAN-6088.

Weakness: CWE-476

Which versions are affected by CVE-2018-1172?

It affects 1 product.

Products include Squid-Cache Squid.

How do I fix CVE-2018-1172?

Apply the vendor's patch.

Is CVE-2018-1172 being exploited?

There is no known exploitation of CVE-2018-1172 in the wild and no public exploit code.

Other vulnerabilities in Squid-Cache Squid

• CVE-2025-62168 Squid vulnerable to information disclosure via authentication credential leakage in error handling Critical 10.0
• CVE-2025-54574 Squid's URN Handling can lead to Buffer Overflow Critical 9.3
• CVE-2026-33526 Squid vulnerable to Denial of Service in ICP Request handling Critical 9.2
• CVE-2026-32748 Squid has Denial of Service in ICP Response handling High 8.7
• CVE-2023-50269 SQUID-2023:10 Denial of Service in HTTP Request parsing High 8.6

All Squid-Cache Squid vulnerabilities

Sources

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

Also known as ALPINE-CVE-2018-1172, DEBIAN-CVE-2018-1172, GHSA-5pj9-pxj3-pc8r, SUSE-SU-2018:1122-1, SUSE-SU-2018:1365-1.