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CVE-2021-47591

5.5 · MEDIUM

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 plu…

Published Jun 19, 2024CWE-476EPSS 0.21%

Overview

CVE-2021-47591 is a medium-severity vulnerability. It was published on June 19, 2024 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/3de0c86d42f841d1d64f316cd949e65c566f0734Refgit.kernel.org/stable/c/404cd9a22150f24acf23a8df2ad0c094ba379f57Refgit.kernel.org/stable/c/3de0c86d42f841d1d64f316cd949e65c566f0734Refgit.kernel.org/stable/c/404cd9a22150f24acf23a8df2ad0c094ba379f57

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47591?

CVE-2021-47591 is a medium-severity vulnerability. It was published on June 19, 2024 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47591?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47591?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-47591?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47591 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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