AUGUST 4, 2026
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Case File

CVE-2021-47593

MEDIUM · CVSS 5.5 EPSS 0.25%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2024-06-19 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 5.5. It affects Linux.

CVE
CVE-2021-47593
Severity
MEDIUM
CVSS
5.5
EPSS
0.25%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: clear 'kern' flag from fallback sockets The mptcp ULP extension relies on sk->sk_sock_kern being set correctly: It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from working for plain tcp sockets (any userspace-exposed socket). But in case of fallback, accept() can return a plain tcp sk. In such case, sk is still tagged as 'kernel' and setsockopt will work. This will crash the kernel, The subflow extension has a NULL ctx->conn mptcp socket: BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0 Call Trace: tcp_data_ready+0xf8/0x370 [..]

Related CVEs

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