{"id":"UBUNTU-CVE-2026-33019","details":"libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1.","modified":"2026-05-20T16:12:43.818262583Z","published":"2026-04-14T22:16:00Z","upstream":["CVE-2026-33019"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33019"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33019"},{"type":"REPORT","url":"https://github.com/saitoha/libsixel/security/advisories/GHSA-c854-ffg9-g72c"},{"type":"REPORT","url":"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"}],"affected":[{"package":{"name":"libsixel","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.2-1","1.5.2-2"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.5.2-2"},{"binary_name":"libsixel1","binary_version":"1.5.2-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.5.2-2","1.7.3-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.7.3-1"},{"binary_name":"libsixel-examples","binary_version":"1.7.3-1"},{"binary_name":"libsixel1","binary_version":"1.7.3-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.2-1","1.8.2-2.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.8.2-2.1"},{"binary_name":"libsixel-examples","binary_version":"1.8.2-2.1"},{"binary_name":"libsixel1","binary_version":"1.8.2-2.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.6-2","1.10.3-2","1.10.3-3"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.10.3-3"},{"binary_name":"libsixel-examples","binary_version":"1.10.3-3"},{"binary_name":"libsixel1","binary_version":"1.10.3-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.10.3-3","1.10.3-3build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.10.3-3build1"},{"binary_name":"libsixel-examples","binary_version":"1.10.3-3build1"},{"binary_name":"libsixel1","binary_version":"1.10.3-3build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.10.5-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.10.5-1"},{"binary_name":"libsixel-examples","binary_version":"1.10.5-1"},{"binary_name":"libsixel1","binary_version":"1.10.5-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}},{"package":{"name":"libsixel","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libsixel?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.10.5-1","1.10.5-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libsixel-bin","binary_version":"1.10.5-1build1"},{"binary_name":"libsixel-examples","binary_version":"1.10.5-1build1"},{"binary_name":"libsixel1","binary_version":"1.10.5-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33019.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}