CVE-2021-47591

MediumCVSS 5.5/10Last modified Jun 17, 2026

Description

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.

Metrics

CVSS 3.1 5.5/10CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness enumeration

CWE-476

Affected software

VendorProductVersions
LinuxLinux>= d9e4c129181004ec94b315b0c9db5eeb09da75e6, < 3de0c86d42f841d1d64f316cd949e65c566f0734; >= d9e4c129181004ec94b315b0c9db5eeb09da75e6, < 404cd9a22150f24acf23a8df2ad0c094ba379f57
LinuxLinux5.13

References

Timeline

Published
Jun 19, 2024
Last modified
Jun 17, 2026
NVD status
Modified

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CVE-2021-47591: Medium severity, CVSS 5.5 | Vulnix