{"id":"UBUNTU-CVE-2026-16434","details":"Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.","modified":"2026-09-02T19:35:29.835491990Z","published":"2026-08-25T02:16:00Z","upstream":["CVE-2026-16434"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-16434"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-16434"},{"type":"REPORT","url":"https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44"}],"affected":[{"package":{"name":"adminer","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.2.1-1","4.2.1-1ubuntu1","4.2.1-1ubuntu1+esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.2.1-1ubuntu1+esm1","binary_name":"adminer"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}},{"package":{"name":"adminer","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.1-2","4.5.0-1","4.6.1-1","4.6.2-1","4.6.2-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.6.2-1ubuntu0.1~esm1","binary_name":"adminer"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}},{"package":{"name":"adminer","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.7.2-1","4.7.4-1","4.7.5-1","4.7.6-1","4.7.6-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.7.6-1ubuntu0.1~esm1","binary_name":"adminer"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}},{"package":{"name":"adminer","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.7.9-2","4.8.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"adminer","binary_version":"4.8.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}},{"package":{"name":"adminer","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.8.1-1","4.8.1-1ubuntu1","4.8.1-2"],"ecosystem_specific":{"binaries":[{"binary_name":"adminer","binary_version":"4.8.1-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}},{"package":{"name":"adminer","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/adminer?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.2.1+dfsg-1","5.3.0+dfsg-1","5.4.0+dfsg-1","5.4.1+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"adminer","binary_version":"5.4.1+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-16434.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}