{"id":"UBUNTU-CVE-2026-6276","details":"Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.","modified":"2026-05-20T22:02:00.410555809Z","published":"2026-04-29T14:00:00Z","related":["USN-8227-1"],"upstream":["CVE-2026-6276"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-6276"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-6276"},{"type":"REPORT","url":"https://curl.se/docs/CVE-2026-6276.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8227-1"}],"affected":[{"package":{"name":"curl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/curl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.81.0-1ubuntu1.24"}]}],"versions":["7.74.0-1.3ubuntu2","7.74.0-1.3ubuntu3","7.80.0-3","7.81.0-1","7.81.0-1ubuntu1.1","7.81.0-1ubuntu1.2","7.81.0-1ubuntu1.3","7.81.0-1ubuntu1.4","7.81.0-1ubuntu1.6","7.81.0-1ubuntu1.7","7.81.0-1ubuntu1.8","7.81.0-1ubuntu1.10","7.81.0-1ubuntu1.11","7.81.0-1ubuntu1.13","7.81.0-1ubuntu1.14","7.81.0-1ubuntu1.15","7.81.0-1ubuntu1.16","7.81.0-1ubuntu1.17","7.81.0-1ubuntu1.18","7.81.0-1ubuntu1.19","7.81.0-1ubuntu1.20","7.81.0-1ubuntu1.21","7.81.0-1ubuntu1.22","7.81.0-1ubuntu1.23"],"ecosystem_specific":{"binaries":[{"binary_name":"curl","binary_version":"7.81.0-1ubuntu1.24"},{"binary_name":"libcurl3-gnutls","binary_version":"7.81.0-1ubuntu1.24"},{"binary_name":"libcurl3-nss","binary_version":"7.81.0-1ubuntu1.24"},{"binary_name":"libcurl4","binary_version":"7.81.0-1ubuntu1.24"}],"availability":"No subscription required","priority_reason":"Upstream defined this as low severity."},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6276.json"}},{"package":{"name":"curl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/curl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.0-2ubuntu10.9"}]}],"versions":["8.2.1-1ubuntu3","8.2.1-1ubuntu3.1","8.4.0-2ubuntu1","8.5.0-2ubuntu1","8.5.0-2ubuntu2","8.5.0-2ubuntu8","8.5.0-2ubuntu9","8.5.0-2ubuntu10","8.5.0-2ubuntu10.1","8.5.0-2ubuntu10.2","8.5.0-2ubuntu10.3","8.5.0-2ubuntu10.4","8.5.0-2ubuntu10.5","8.5.0-2ubuntu10.6","8.5.0-2ubuntu10.7","8.5.0-2ubuntu10.8"],"ecosystem_specific":{"priority_reason":"Upstream defined this as low severity.","binaries":[{"binary_name":"curl","binary_version":"8.5.0-2ubuntu10.9"},{"binary_name":"libcurl3t64-gnutls","binary_version":"8.5.0-2ubuntu10.9"},{"binary_version":"8.5.0-2ubuntu10.9","binary_name":"libcurl4t64"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6276.json"}},{"package":{"name":"curl","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/curl?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.14.1-2ubuntu1.3"}]}],"versions":["8.12.1-3ubuntu1","8.13.0-5ubuntu1","8.14.1-1ubuntu2","8.14.1-1ubuntu3","8.14.1-2ubuntu1","8.14.1-2ubuntu1.1","8.14.1-2ubuntu1.2"],"ecosystem_specific":{"availability":"No subscription required","priority_reason":"Upstream defined this as low severity.","binaries":[{"binary_version":"8.14.1-2ubuntu1.3","binary_name":"curl"},{"binary_name":"libcurl3t64-gnutls","binary_version":"8.14.1-2ubuntu1.3"},{"binary_version":"8.14.1-2ubuntu1.3","binary_name":"libcurl4t64"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6276.json"}},{"package":{"name":"curl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/curl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.18.0-1ubuntu2.1"}]}],"versions":["8.14.1-2ubuntu1","8.17.0-1ubuntu1","8.18.0-1ubuntu1","8.18.0-1ubuntu2"],"ecosystem_specific":{"availability":"No subscription required","priority_reason":"Upstream defined this as low severity.","binaries":[{"binary_version":"8.18.0-1ubuntu2.1","binary_name":"curl"},{"binary_name":"libcurl3t64-gnutls","binary_version":"8.18.0-1ubuntu2.1"},{"binary_name":"libcurl4t64","binary_version":"8.18.0-1ubuntu2.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6276.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"low"}]}