{"id":"UBUNTU-CVE-2026-56855","details":"Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.","modified":"2026-09-16T11:36:40Z","published":"2026-09-02T20:17:00Z","upstream":["CVE-2026-56855"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-56855"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-56855"},{"type":"REPORT","url":"https://go.dev/cl/826524"},{"type":"REPORT","url":"https://go.dev/issue/81317"},{"type":"REPORT","url":"https://groups.google.com/g/golang-announce/c/1y3fb2np35U"},{"type":"REPORT","url":"https://pkg.go.dev/vuln/GO-2026-6355"}],"affected":[{"package":{"name":"golang-defaults","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/golang-defaults?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:1.6-1ubuntu3","2:1.6-1ubuntu4"],"ecosystem_specific":{"binaries":[{"binary_name":"golang","binary_version":"2:1.6-1ubuntu4"},{"binary_name":"golang-any","binary_version":"2:1.6-1ubuntu4"},{"binary_version":"2:1.6-1ubuntu4","binary_name":"golang-go"},{"binary_name":"golang-race-detector-runtime","binary_version":"2:1.6-1ubuntu4"},{"binary_name":"golang-src","binary_version":"2:1.6-1ubuntu4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-defaults","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/golang-defaults?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:1.8~1ubuntu1","2:1.9~2ubuntu1","2:1.10~4ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"gccgo-go","binary_version":"2:1.10~4ubuntu1"},{"binary_name":"golang","binary_version":"2:1.10~4ubuntu1"},{"binary_name":"golang-any","binary_version":"2:1.10~4ubuntu1"},{"binary_name":"golang-go","binary_version":"2:1.10~4ubuntu1"},{"binary_name":"golang-race-detector-runtime","binary_version":"2:1.10~4ubuntu1"},{"binary_version":"2:1.10~4ubuntu1","binary_name":"golang-src"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-defaults","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/golang-defaults?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2:1.12~1ubuntu1","2:1.13~1ubuntu1","2:1.13~1ubuntu2"],"ecosystem_specific":{"binaries":[{"binary_name":"gccgo-go","binary_version":"2:1.13~1ubuntu2"},{"binary_name":"golang","binary_version":"2:1.13~1ubuntu2"},{"binary_name":"golang-any","binary_version":"2:1.13~1ubuntu2"},{"binary_name":"golang-go","binary_version":"2:1.13~1ubuntu2"},{"binary_name":"golang-race-detector-runtime","binary_version":"2:1.13~1ubuntu2"},{"binary_name":"golang-src","binary_version":"2:1.13~1ubuntu2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-1.20","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/golang-1.20?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.20.3-1ubuntu0.1~20.04","1.20.3-1ubuntu0.1~20.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-1.20","binary_version":"1.20.3-1ubuntu0.1~20.04.1"},{"binary_name":"golang-1.20-go","binary_version":"1.20.3-1ubuntu0.1~20.04.1"},{"binary_name":"golang-1.20-src","binary_version":"1.20.3-1ubuntu0.1~20.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-1.21","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/golang-1.21?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.21.1-1~ubuntu20.04.1","1.21.1-1~ubuntu20.04.2","1.21.1-1~ubuntu20.04.3"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-1.21","binary_version":"1.21.1-1~ubuntu20.04.3"},{"binary_name":"golang-1.21-go","binary_version":"1.21.1-1~ubuntu20.04.3"},{"binary_version":"1.21.1-1~ubuntu20.04.3","binary_name":"golang-1.21-src"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-1.22","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/golang-1.22?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.22.2-2~20.04.1","1.22.2-2~20.04.2"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-1.22","binary_version":"1.22.2-2~20.04.2"},{"binary_name":"golang-1.22-go","binary_version":"1.22.2-2~20.04.2"},{"binary_version":"1.22.2-2~20.04.2","binary_name":"golang-1.22-src"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-56855.json"}},{"package":{"name":"golang-1.17","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/golang-1.17?arch=source&dis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