CVE-2021-47591 mptcp: remove tcp ulp setsockopt support
A null pointer dereference in the Linux kernel MPTCP module allows local attackers to cause a system crash via TCP_ULP setsockopt.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47591?
CVE-2021-47591 is a medium-severity vulnerability in Linux kernel, published on 19 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2021-47591?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47591?
Apply the vendor's patch.
Is CVE-2021-47591 being exploited?
There is no known exploitation of CVE-2021-47591 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47591, GHSA-9hfm-p748-vm54, UBUNTU-CVE-2021-47591.