{"id":"UBUNTU-CVE-2026-33526","details":"Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.","modified":"2026-04-13T12:52:14.340815Z","published":"2026-03-26T01:16:00Z","related":["USN-8157-1"],"upstream":["CVE-2026-33526"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33526"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33526"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2026/03/25/2"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8157-1"}],"affected":[{"package":{"name":"squid3","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/squid3@3.5.12-1ubuntu7.16+esm6?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.3.8-1ubuntu16","3.3.8-1ubuntu17","3.5.12-1ubuntu6","3.5.12-1ubuntu7","3.5.12-1ubuntu7.1","3.5.12-1ubuntu7.2","3.5.12-1ubuntu7.3","3.5.12-1ubuntu7.4","3.5.12-1ubuntu7.5","3.5.12-1ubuntu7.6","3.5.12-1ubuntu7.7","3.5.12-1ubuntu7.8","3.5.12-1ubuntu7.9","3.5.12-1ubuntu7.10","3.5.12-1ubuntu7.11","3.5.12-1ubuntu7.12","3.5.12-1ubuntu7.13","3.5.12-1ubuntu7.14","3.5.12-1ubuntu7.15","3.5.12-1ubuntu7.16","3.5.12-1ubuntu7.16+esm1","3.5.12-1ubuntu7.16+esm2","3.5.12-1ubuntu7.16+esm3","3.5.12-1ubuntu7.16+esm4","3.5.12-1ubuntu7.16+esm5","3.5.12-1ubuntu7.16+esm6"],"ecosystem_specific":{"binaries":[{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squid"},{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squid-cgi"},{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squid-common"},{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squid-purge"},{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squid3"},{"binary_version":"3.5.12-1ubuntu7.16+esm6","binary_name":"squidclient"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33526.json"}},{"package":{"name":"squid3","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/squid3@3.5.27-1ubuntu1.14+esm5?arch=source&distro=esm-infra/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.5.23-5ubuntu1","3.5.23-5ubuntu2","3.5.27-1ubuntu1","3.5.27-1ubuntu1.1","3.5.27-1ubuntu1.2","3.5.27-1ubuntu1.3","3.5.27-1ubuntu1.4","3.5.27-1ubuntu1.5","3.5.27-1ubuntu1.6","3.5.27-1ubuntu1.7","3.5.27-1ubuntu1.8","3.5.27-1ubuntu1.9","3.5.27-1ubuntu1.10","3.5.27-1ubuntu1.11","3.5.27-1ubuntu1.12","3.5.27-1ubuntu1.13","3.5.27-1ubuntu1.14","3.5.27-1ubuntu1.14+esm1","3.5.27-1ubuntu1.14+esm2","3.5.27-1ubuntu1.14+esm3","3.5.27-1ubuntu1.14+esm4","3.5.27-1ubuntu1.14+esm5"],"ecosystem_specific":{"binaries":[{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squid"},{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squid-cgi"},{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squid-common"},{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squid-purge"},{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squid3"},{"binary_version":"3.5.27-1ubuntu1.14+esm5","binary_name":"squidclient"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33526.json"}},{"package":{"name":"squid","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/squid@4.10-1ubuntu1.13+esm2?arch=source&distro=esm-infra/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.8-1ubuntu2","4.8-1ubuntu3","4.9-2ubuntu1","4.9-2ubuntu2","4.9-2ubuntu3","4.9-2ubuntu4","4.10-1ubuntu1","4.10-1ubuntu1.1","4.10-1ubuntu1.2","4.10-1ubuntu1.3","4.10-1ubuntu1.4","4.10-1ubuntu1.5","4.10-1ubuntu1.6","4.10-1ubuntu1.7","4.10-1ubuntu1.8","4.10-1ubuntu1.9","4.10-1ubuntu1.10","4.10-1ubuntu1.11","4.10-1ubuntu1.12","4.10-1ubuntu1.13","4.10-1ubuntu1.13+esm1","4.10-1ubuntu1.13+esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"4.10-1ubuntu1.13+esm2","binary_name":"squid"},{"binary_version":"4.10-1ubuntu1.13+esm2","binary_name":"squid-cgi"},{"binary_version":"4.10-1ubuntu1.13+esm2","binary_name":"squid-common"},{"binary_version":"4.10-1ubuntu1.13+esm2","binary_name":"squid-purge"},{"binary_version":"4.10-1ubuntu1.13+esm2","binary_name":"squidclient"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33526.json"}},{"package":{"name":"squid","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/squid@5.9-0ubuntu0.22.04.5?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.9-0ubuntu0.22.04.5"}]}],"versions":["4.13-10ubuntu5","5.2-1ubuntu1","5.2-1ubuntu3","5.2-1ubuntu4","5.2-1ubuntu4.1","5.2-1ubuntu4.2","5.2-1ubuntu4.3","5.7-0ubuntu0.22.04.1","5.7-0ubuntu0.22.04.2","5.7-0ubuntu0.22.04.3","5.7-0ubuntu0.22.04.4","5.9-0ubuntu0.22.04.1","5.9-0ubuntu0.22.04.2","5.9-0ubuntu0.22.04.3","5.9-0ubuntu0.22.04.4"],"ecosystem_specific":{"availability":"No subscription 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