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CVE-2021-47243

7.1 · HIGH

In the Linux kernel, the following vulnerability has been resolved: sch_cake: Fix out of bounds when parsing TCP options and header The TCP option parser in cake qdisc (cake_get_tcpopt and cake_t…

Published May 21, 2024CWE-125EPSS 0.26%

Overview

CVE-2021-47243 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. 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:

sch_cake: Fix out of bounds when parsing TCP options and header

The TCP option parser in cake qdisc (cake_get_tcpopt and

cake_tcph_may_drop) could read one byte out of bounds. When the length

is 1, the execution flow gets into the loop, reads one byte of the

opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads

one more byte, which exceeds the length of 1.

This fix is inspired by commit 9609dad263f8 ("ipv4: tcp_input: fix stack

out of bounds when parsing TCP options.").

v2 changes:

Added doff validation in cake_get_tcphdr to avoid parsing garbage as TCP

header. Although it wasn't strictly an out-of-bounds access (memory was

allocated), garbage values could be read where CAKE expected the TCP

header if doff was smaller than 5.

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/3371392c60e2685af30bd4547badd880f5df2b3fRefgit.kernel.org/stable/c/3b491dd593d582ceeb27aa617600712a6bd14246Refgit.kernel.org/stable/c/4cefa061fc63f4d2dff5ab4083f43857cd7a2335Refgit.kernel.org/stable/c/595897ef118d6fe66690c4fc5b572028c9da95b7Refgit.kernel.org/stable/c/ba91c49dedbde758ba0b72f57ac90b06ddf8e548Refgit.kernel.org/stable/c/3371392c60e2685af30bd4547badd880f5df2b3fRefgit.kernel.org/stable/c/3b491dd593d582ceeb27aa617600712a6bd14246Refgit.kernel.org/stable/c/4cefa061fc63f4d2dff5ab4083f43857cd7a2335Refgit.kernel.org/stable/c/595897ef118d6fe66690c4fc5b572028c9da95b7Refgit.kernel.org/stable/c/ba91c49dedbde758ba0b72f57ac90b06ddf8e548

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47243?

CVE-2021-47243 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.1 (HIGH).

How severe is CVE-2021-47243?

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47243?

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-2021-47243?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47243 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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