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Review reviewHigh

CVE-2021-47243

Linux Linux, linux kernel

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 i...

CVSS
7.1
EPSS
-
- percentile
CISA KEV
Not listed
Published
2024.05.22
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.1

Vulnerability overview

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 i...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= 8b7138814f29933898ecd31dfc83e35a30ee69f5 < 595897ef118d6fe66690c4fc5b572028c9da95b7, >= 8b7138814f29933898ecd31dfc83e35a30ee69f5 < 4cefa061fc63f4d2dff5ab4083f43857cd7a2335, >= 8b7138814f29933898ecd31dfc83e35a30ee69f5 < 3b491dd593d582ceeb27aa617600712a6bd14246, >= 8b7138814f29933898ecd31dfc83e35a30ee69f5 < 3371392c60e2685af30bd4547badd880f5df2b3f, >= 8b7138814f29933898ecd31dfc83e35a30ee69f5 < ba91c49dedbde758ba0b72f57ac90b06ddf8e548, >= 4.19, >= 4.19 < 4.19.196, >= 4.20 < 5.4.128, >= 5.5 < 5.10.46, >= 5.11 < 5.12.13, 5.13
Fixed versions
4.19.196, 5.4.128, 5.10.46, 5.12.13

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
CWE
CWE-125