Bug 2524438 (CVE-2026-80586)

Summary: CVE-2026-80586 kernel: mptcp: options: reset DSS fields in case of unexpected size
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. A remote attacker could send a malformed Data Sequence Signal (DSS) with an incorrect size. This could lead to inconsistencies or access to uninitialized data within the kernel.
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Description OSIDB Bzimport 2026-08-26 14:53:12 UTC 
In the Linux kernel, the following vulnerability has been resolved:

mptcp: options: reset DSS fields in case of unexpected size

A remote peer could send a malformed DSS with a wrong size, followed by
another DSS or MPC + Data. In this case, the first suboption will be
ignored, but leaving some fields written, which could lead to
inconsistency or access uninitialized data.

Explicitly reset the fields that could have been modified in case of
unexpected size.
Comment 1 gkamathe 2026-08-27 07:19:52 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082616-CVE-2026-80586-008c@gregkh/T