{"id":"DEBIAN-CVE-2021-47591","details":"In the Linux kernel, the following vulnerability has been resolved:  mptcp: remove tcp ulp setsockopt support  TCP_ULP setsockopt cannot be used for mptcp because its already used internally to plumb subflow (tcp) sockets to the mptcp layer.  syzbot managed to trigger a crash for mptcp connections that are in fallback mode:  KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0 RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline] [..]  __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline]  tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160  do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391  mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638  Remove support for TCP_ULP setsockopt.","modified":"2026-09-01T20:03:23.265626284Z","published":"2024-06-19T15:15:53.700Z","upstream":["CVE-2021-47591"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2021-47591"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47591.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47591.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.15-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47591.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}