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.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2025-989300 advisory.

    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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2025-987131 advisory.

    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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2021-47243)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
273999	Unity Linux 20.1070a Security Update: kernel (UTSA-2025-989300)	Nessus	Unity Linux Local Security Checks	high
269102	Unity Linux 20.1070e Security Update: kernel (UTSA-2025-987131)	Nessus	Unity Linux Local Security Checks	high
230108	Linux Distros Unpatched Vulnerability : CVE-2021-47243	Nessus	Misc.	high

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CVE-2021-47243

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