{"id":"UBUNTU-CVE-2026-56123","details":"socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes_to_read value that is implicitly converted to size_t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.","modified":"2026-07-06T20:30:39.630926520Z","published":"2026-06-25T17:17:00Z","related":["USN-8511-1"],"upstream":["CVE-2026-56123"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-56123"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-56123"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8511-1"}],"affected":[{"package":{"name":"socat","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/socat?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.0.0-4ubuntu0.1"}]}],"versions":["1.7.4.4-2","1.8.0.0-4","1.8.0.0-4build1","1.8.0.0-4build2","1.8.0.0-4build3"],"ecosystem_specific":{"binaries":[{"binary_version":"1.8.0.0-4ubuntu0.1","binary_name":"socat"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56123.json"}},{"package":{"name":"socat","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/socat?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.0.2-1","1.8.0.3-1","1.8.0.3-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"socat","binary_version":"1.8.0.3-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56123.json"}},{"package":{"name":"socat","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/socat?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.1-1ubuntu0.1"}]}],"versions":["1.8.0.3-1build1","1.8.1.0-1","1.8.1.0-2","1.8.1.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"socat","binary_version":"1.8.1.1-1ubuntu0.1"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56123.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}