{"id":"CVE-2026-56123","aliases":["ALPINE-CVE-2026-56123","BELL-CVE-2026-56123","DEBIAN-CVE-2026-56123","EUVD-2026-39455","GHSA-6r8c-w5mj-43hv","MGASA-2026-0290","OESA-2026-2942","OESA-2026-2943","ROOT-OS-DEBIAN-13-CVE-2026-56123","UBUNTU-CVE-2026-56123","USN-8511-1","openSUSE-SU-2026:11151-1"],"status":"published","title":"socat 1.8.0.0 - 1.8.1.1 Heap Buffer Overflow via SOCKS5 Reply Parser","description":"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.","severity":{"version":"4.0","score":9.2,"vector":"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","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00314,"percentile":0.24706,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-122"],"published":"2026-06-25T15:43:19Z","modified":"2026-10-09T13:00:17Z","fixes":[{"ecosystem":"Alpine:v3.21","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Alpaquita:25","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Alpaquita:stream","package":"socat","fixed_in":["1.8.1.2-r0"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"socat","fixed_in":["1.8.0.3-1+deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"socat","fixed_in":["1.8.1.3-1"],"sources":["osv"]},{"ecosystem":"Mageia:10","package":"socat","fixed_in":["1.8.1.0-1.1.mga10"],"sources":["osv"]},{"ecosystem":"Mageia:9","package":"socat","fixed_in":["1.8.0.2-1.1.mga9"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP3","package":"socat","fixed_in":["1.8.1.3-1.oe2403sp3"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP1","package":"socat","fixed_in":["1.8.1.3-1.oe2403sp1"],"sources":["osv"]},{"ecosystem":"Ubuntu:24.04:LTS","package":"socat","fixed_in":["1.8.0.0-4ubuntu0.1"],"sources":["osv"]},{"ecosystem":"Ubuntu:26.04:LTS","package":"socat","fixed_in":["1.8.1.1-1ubuntu0.1"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"socat","fixed_in":["1.8.1.3-1.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.21","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Alpaquita:25","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.3-r0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Alpaquita:stream","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.8.0.0-r0"},{"fixed":"1.8.1.2-r0"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.0.3-1+deb13u1"}]}],"versions":["1.8.0.3-1"]},{"source":"osv","ecosystem":"Debian:14","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.3-1"}]}],"versions":["1.8.0.3-1","1.8.1.0-1","1.8.1.0-2","1.8.1.1-1","1.8.1.1-2"]},{"source":"osv","ecosystem":"Mageia:10","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.0-1.1.mga10"}]}]},{"source":"osv","ecosystem":"Mageia:9","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.0.2-1.1.mga9"}]}]},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP3","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.3-1.oe2403sp3"}]}]},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP1","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.3-1.oe2403sp1"}]}]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"socat","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"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.0.2-1","1.8.0.3-1","1.8.0.3-1build1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"socat","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"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"socat","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"],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"socat","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"],"bundled":2},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"socat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1.3-1.1"}]}]}],"products":[{"vendor":"dest-unreach","product":"socat"},{"vendor":"socat","product":"socat"}],"references":[{"url":"http://www.dest-unreach.org/socat/CHANGES","tags":["release-notes","patch","Release Notes"]},{"url":"https://www.vulncheck.com/advisories/socat-heap-buffer-overflow-via-socks5-reply-parser","tags":["third-party-advisory","Third Party Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56123","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-6r8c-w5mj-43hv"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-56123","tags":["advisory"]},{"url":"https://docs.bell-sw.com/security/cves/CVE-2026-56123","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-56123","tags":["advisory"]},{"url":"https://advisories.mageia.org/MGASA-2026-0290.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=35794","tags":["report"]},{"url":"https://lists.opensuse.org/archives/list/security-announce@lists.opensuse.org/message/F6FLUO6FYZ6TSE43PLY7QJGUX4N2JXWW/","tags":["web"]},{"url":"https://ubuntu.com/security/notices/USN-8511-1","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2942","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2943","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-56123","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56123","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2024-54661","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-56123","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-56123","title":"socat 1.8.0.0 - 1.8.1.1 Heap Buffer Overflow via SOCKS5 Reply Parser","description":"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.","status":"published","published":"2026-06-25T15:43:19.58Z","modified":"2026-07-14T21:34:06.653Z","cvss":[{"version":"4.0","score":9.2,"vector":"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","level":"critical","assessor":"cna"},{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-122"],"updated_at":"2026-11-02T13:36:51.6229Z"}],"euvd":[{"id":"EUVD-2026-39455","description":"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.","status":"published","published":"2026-06-25T15:43:19Z","modified":"2026-07-14T21:34:06Z","cvss":[{"version":"4.0","score":9.2,"vector":"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","level":"critical"}],"updated_at":"2026-11-02T18:19:58.306277Z"}],"ghsa":[{"id":"GHSA-6r8c-w5mj-43hv","title":"socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that...","description":"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.","status":"published","published":"2026-06-25T18:30:41Z","modified":"2026-06-25T18:30:47Z","cvss":[{"version":"4.0","score":9.2,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical"},{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-122"],"updated_at":"2026-11-02T15:08:59.328511Z"}],"nvd":[{"id":"CVE-2026-56123","description":"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.","status":"published","published":"2026-06-25T17:17:01.967Z","modified":"2026-06-26T16:50:16.103Z","cvss":[{"version":"4.0","score":9.2,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"critical","assessor":"secondary"},{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"}],"cwes":["CWE-122"],"updated_at":"2026-11-02T14:12:26.045561Z"}],"osv":[{"id":"ALPINE-CVE-2026-56123","description":"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.","status":"published","published":"2026-06-25T17:17:01.967Z","modified":"2026-10-01T02:17:49.353701218Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:27:50.764331Z"},{"id":"BELL-CVE-2026-56123","status":"published","published":"2026-06-26T17:31:34.284729Z","modified":"2026-06-28T20:55:00.648063Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:28:24.657778Z"},{"id":"DEBIAN-CVE-2026-56123","description":"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.","status":"published","published":"2026-06-25T17:17:01.967Z","modified":"2026-10-01T03:03:27.070939893Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:45:57.590991Z"},{"id":"OESA-2026-2942","title":"socat security update","description":"Socat is a relay for bidirectional data transfer between two independent data channels. Each of these data channels may be a file, pipe, device (serial line etc. or a pseudo terminal), a socket (UNIX, IP4, IP6 - raw, UDP, TCP), an SSL socket, proxy CONNECT connection, a file descriptor (stdin etc.), the GNU line editor (readline), a program, or a combination of two of these.\r\n\r\nSecurity Fix(es):\n\nsocat 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.(CVE-2026-56123)","status":"published","published":"2026-07-09T11:11:50Z","modified":"2026-08-18T01:21:15.865017367Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:52:46.823443Z"},{"id":"OESA-2026-2943","title":"socat security update","description":"Socat is a relay for bidirectional data transfer between two independent data channels. Each of these data channels may be a file, pipe, device (serial line etc. or a pseudo terminal), a socket (UNIX, IP4, IP6 - raw, UDP, TCP), an SSL socket, proxy CONNECT connection, a file descriptor (stdin etc.), the GNU line editor (readline), a program, or a combination of two of these.\r\n\r\nSecurity Fix(es):\n\nsocat 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.(CVE-2026-56123)","status":"published","published":"2026-07-09T11:11:51Z","modified":"2026-08-18T01:21:16.959990011Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:52:46.823443Z"},{"id":"UBUNTU-CVE-2026-56123","description":"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.","status":"published","published":"2026-06-25T17:17:00Z","modified":"2026-07-06T20:30:34.894825014Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"high"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"},{"version":"4.0","score":9.2,"vector":"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","level":"critical"}],"updated_at":"2026-11-02T16:56:41.382716Z"},{"id":"MGASA-2026-0290","title":"Updated socat package fixes a security vulnerability","description":"The updated package fixes a security vulnerability:\nHeap Buffer Overflow via SOCKS5 Reply Parser. (CVE-2026-56123)\n","status":"published","published":"2026-07-23T17:45:56Z","modified":"2026-07-23T18:00:05.162529504Z","updated_at":"2026-11-02T15:49:43.795591Z"},{"id":"openSUSE-SU-2026:11151-1","title":"socat-1.8.1.3-1.1 on GA media","description":"These are all security issues fixed in the socat-1.8.1.3-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-06-29T00:00:00Z","modified":"2026-06-30T09:15:07.517369819Z","updated_at":"2026-11-02T16:58:38.95195Z"},{"id":"ROOT-OS-DEBIAN-13-CVE-2026-56123","title":"CVE-2026-56123 in socat - Patched by Root","description":"Root has patched CVE-2026-56123 in the socat package for Root:Debian:13. Multiple fixed versions available.","status":"withdrawn","published":"2026-08-24T16:07:53Z","modified":"2026-10-09T13:00:17.28402034Z","updated_at":"2026-11-02T15:53:33.681527Z"},{"id":"USN-8511-1","title":"socat vulnerabilities","description":"It was discovered that socat incorrectly handled the SOCKS5 proxy server\nreply parser. A remote attacker could possibly use this issue to execute\narbitrary code. (CVE-2026-56123)\n\nIt was discovered that socat incorrectly handled a sample script. A local\nattacker could possibly use this issue to overwrite arbitrary files. This\nissue only affected Ubuntu 24.04 LTS. (CVE-2024-54661)","status":"published","published":"2026-07-06T12:37:17Z","modified":"2026-07-06T20:44:29.593211784Z","updated_at":"2026-11-02T16:58:25.103481Z"}]}}