{"id":"UBUNTU-CVE-2026-44638","details":"libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From  to 1.8.7-r1, a wrong NULL check after an allocation call in sixel_decode_raw and sixel_decode causes a NULL pointer dereference whenever the allocation fails. The check tests the address of the output parameter (always non-NULL) instead of the value the malloc returned. On allocation failure, the function continues and writes through a NULL pointer, crashing the process. This is a denial of service against any caller of these public APIs that hits a low-memory condition. This vulnerability is fixed in 1.8.7-r2.","modified":"2026-05-20T22:03:07.768253492Z","published":"2026-05-14T20:17:00Z","upstream":["CVE-2026-44638"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-44638"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-44638"},{"type":"REPORT","url":"https://github.com/saitoha/libsixel/security/advisories/GHSA-wpx3-h5g8-qr3w"}],"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_version":"1.5.2-2","binary_name":"libsixel-bin"},{"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-2026-44638.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_version":"1.7.3-1","binary_name":"libsixel1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44638.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_version":"1.8.2-2.1","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"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44638.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_version":"1.10.3-3","binary_name":"libsixel-bin"},{"binary_version":"1.10.3-3","binary_name":"libsixel-examples"},{"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-2026-44638.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_version":"1.10.3-3build1","binary_name":"libsixel-examples"},{"binary_version":"1.10.3-3build1","binary_name":"libsixel1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44638.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_version":"1.10.5-1","binary_name":"libsixel-bin"},{"binary_version":"1.10.5-1","binary_name":"libsixel-examples"},{"binary_version":"1.10.5-1","binary_name":"libsixel1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44638.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_version":"1.10.5-1build1","binary_name":"libsixel-bin"},{"binary_version":"1.10.5-1build1","binary_name":"libsixel-examples"},{"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-2026-44638.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L"},{"type":"Ubuntu","score":"medium"}]}