Bug 2521399 (CVE-2026-74585)

Summary: CVE-2026-74585 kernel: thunderbolt: Bound the DROM dual link port number before indexing sw->ports
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
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's Thunderbolt driver. A malicious or malformed Thunderbolt device can provide an invalid port number, leading to an out-of-bounds memory access. This can result in memory corruption and potentially lead to a denial of service or other unspecified impacts.
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Description OSIDB Bzimport 2026-08-22 15:43:38 UTC 
In the Linux kernel, the following vulnerability has been resolved:

thunderbolt: Bound the DROM dual link port number before indexing sw->ports

tb_drom_parse_entry_port() validates the device-supplied header->index
against sw->config.max_port_number before indexing sw->ports[], but the
sibling field entry->dual_link_port_nr -- a 6-bit value also read from
the DROM -- indexes the same array with no such check. A malicious or
malformed Thunderbolt device can set dual_link_port_nr beyond the
allocated sw->ports[] (max_port_number + 1 entries), producing an
out-of-bounds tb_port pointer that is stored and later dereferenced.

Reject a port entry whose dual_link_port_nr exceeds max_port_number,
the same bound already applied to header->index.
Comment 1 Mauro Matteo Cascella 2026-08-24 11:04:06 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082209-CVE-2026-74585-8fe6@gregkh/T