Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a NULL pointer dereference bug Squid is vulnerable to a Denial of Service attack against Squids Gopher gateway. The gopher protocol is always available and enabled in Squid prior to Squid 6.0.1. Responses triggering this bug are possible to be received from any gopher server, even those without malicious intent. Gopher support has been removed in Squid version 6.0.1. Users are advised to upgrade. Users unable to upgrade should reject all gopher URL requests.
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Squid | Squid-cache | * | 6.0.1 (excluding) |
| Squid | Ubuntu | bionic | * |
| Squid | Ubuntu | focal | * |
| Squid | Ubuntu | jammy | * |
| Squid | Ubuntu | lunar | * |
| Squid | Ubuntu | trusty | * |
| Squid | Ubuntu | upstream | * |
| Squid | Ubuntu | xenial | * |
| Squid3 | Ubuntu | bionic | * |
| Squid3 | Ubuntu | esm-infra/bionic | * |
| Squid3 | Ubuntu | esm-infra/xenial | * |
| Squid3 | Ubuntu | trusty | * |
| Squid3 | Ubuntu | xenial | * |
| Red Hat Enterprise Linux 7 | RedHat | squid-7:3.5.20-17.el7_9.10 | * |
| Red Hat Enterprise Linux 8 | RedHat | squid:4-8090020231207155957.a75119d5 | * |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | RedHat | squid:4-8020020240122164331.4cda2c84 | * |
| Red Hat Enterprise Linux 8.2 Telecommunications Update Service | RedHat | squid:4-8020020240122164331.4cda2c84 | * |
| Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions | RedHat | squid:4-8020020240122164331.4cda2c84 | * |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | RedHat | squid:4-8040020240122165847.522a0ee4 | * |
| Red Hat Enterprise Linux 8.4 Telecommunications Update Service | RedHat | squid:4-8040020240122165847.522a0ee4 | * |
| Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions | RedHat | squid:4-8040020240122165847.522a0ee4 | * |
| Red Hat Enterprise Linux 8.6 Extended Update Support | RedHat | squid:4-8060020231222131040.ad008a3a | * |
| Red Hat Enterprise Linux 8.8 Extended Update Support | RedHat | squid:4-8080020231222130009.63b34585 | * |
| Red Hat Enterprise Linux 9 | RedHat | squid-7:5.5-6.el9_3.5 | * |
| Red Hat Enterprise Linux 9.0 Extended Update Support | RedHat | squid-7:5.2-1.el9_0.4 | * |
| Red Hat Enterprise Linux 9.2 Extended Update Support | RedHat | squid-7:5.5-5.el9_2.3 | * |