{"id":"UBUNTU-CVE-2026-123784","details":"Fluxbox through 1.3.7 contains an OS command injection vulnerability in RootTheme::reconfigTheme() that allows attackers to execute commands via crafted style background values. Attackers can embed shell metacharacters in background pixmap paths, random directories, or gradient texture text, which are concatenated unescaped into an fbsetbg command run via $SHELL -c when the style loads.","modified":"2026-11-10T02:50:22.587329814Z","published":"2026-11-09T00:00:00Z","upstream":["CVE-2026-123784"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-123784"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-123784"},{"type":"REPORT","url":"https://github.com/fluxbox/fluxbox/pull/89"},{"type":"REPORT","url":"https://github.com/fluxbox/fluxbox"},{"type":"REPORT","url":"https://github.com/fluxbox/fluxbox/blob/Release-1_3_7/src/RootTheme.cc#L192-L264"},{"type":"REPORT","url":"https://github.com/fluxbox/fluxbox/commit/270bfbc28573037c9b8458488d193b219e33889f"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/fluxbox-through-1.3.7-os-command-injection-via-style-background-values"}],"affected":[{"package":{"name":"fluxbox","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.5-2","binary_name":"fluxbox"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-2","1.3.5-2build1"],"ecosystem_specific":{"binaries":[{"binary_name":"fluxbox","binary_version":"1.3.5-2build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-2build1","1.3.5-2build2"],"ecosystem_specific":{"binaries":[{"binary_name":"fluxbox","binary_version":"1.3.5-2build2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.5-2build2","1.3.5-2.1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.5-2.1","binary_name":"fluxbox"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.7-1","1.3.7-1build1","1.3.7-1build2"],"ecosystem_specific":{"binaries":[{"binary_name":"fluxbox","binary_version":"1.3.7-1build2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.7-1build3"],"ecosystem_specific":{"binaries":[{"binary_name":"fluxbox","binary_version":"1.3.7-1build3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}},{"package":{"name":"fluxbox","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/fluxbox?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.7-1build2","1.3.7-1build3"],"ecosystem_specific":{"binaries":[{"binary_name":"fluxbox","binary_version":"1.3.7-1build3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123784.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}