https://vulnerability.circl.lu Contains only the most 10 recent entries. http://www.rssboard.org/rss-specification python-feedgen en Thu, 01 Oct 2026 08:35:52 +0000 https://vulnerability.circl.lu/vuln/cve-2021-47593 <p><strong>Affected:</strong> Linux</p> <p>In the Linux kernel, the following vulnerability has been resolved:</p> <p>mptcp: clear &#39;kern&#39; flag from fallback sockets</p> <p>The mptcp ULP extension relies on sk-&gt;sk_sock_kern being set correctly: It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, &#34;mptcp&#34;, 6); from working for plain tcp sockets (any userspace-exposed socket).</p> <p>But in case of fallback, accept() can return a plain tcp sk. In such case, sk is still tagged as &#39;kernel&#39; and setsockopt will work.</p> <p>This will crash the kernel, The subflow extension has a NULL ctx-&gt;conn mptcp socket:</p> <p>BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0 Call Trace: tcp_data_ready+0xf8/0x370 [..]</p> <p><strong>Affected:</strong> Linux</p> <p>In the Linux kernel, the following vulnerability has been resolved:</p> <p>mptcp: clear &#39;kern&#39; flag from fallback sockets</p> <p>The mptcp ULP extension relies on sk-&gt;sk_sock_kern being set correctly: It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, &#34;mptcp&#34;, 6); from working for plain tcp sockets (any userspace-exposed socket).</p> <p>But in case of fallback, accept() can return a plain tcp sk. In such case, sk is still tagged as &#39;kernel&#39; and setsockopt will work.</p> <p>This will crash the kernel, The subflow extension has a NULL ctx-&gt;conn mptcp socket:</p> <p>BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0 Call Trace: tcp_data_ready+0xf8/0x370 [..]</p> https://vulnerability.circl.lu/vuln/cve-2021-47593