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CVE-2021-47593

MEDIUMCVSS 5.5/10EPSS 0.25%

Last modified

CVE-2021-47593 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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 [..]. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

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 [..]

Metrics

CVSS 3.1
5.5/10

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

EPSS Probability
0.25%

15.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel>= 5.6, < 5.10.88—
LinuxLinux Kernel>= 5.11, < 5.15.11—
LinuxLinux Kernel5.16Rc1

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-47593?
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 [..]
How severe is CVE-2021-47593?
CVE-2021-47593 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.
How do I fix CVE-2021-47593?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-47593?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST