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CVE-2021-47243

HIGHCVSS 7.1/10EPSS 0.26%

Last modified

CVE-2021-47243 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.1/10

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

EPSS Probability
0.26%

17.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel>= 4.19, < 4.19.196—
LinuxLinux Kernel>= 4.20, < 5.4.128—
LinuxLinux Kernel>= 5.5, < 5.10.46—
LinuxLinux Kernel>= 5.11, < 5.12.13—
LinuxLinux Kernel5.13Rc1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2021-47243?
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.
How severe is CVE-2021-47243?
CVE-2021-47243 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.
How do I fix CVE-2021-47243?
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-2021-47243?

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Source: NVD / NIST