CVE-2026-74585 thunderbolt: Bound the DROM dual link port number before indexing sw->ports
A malicious Thunderbolt device can trigger an out-of-bounds write in the Linux kernel, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-74585?
CVE-2026-74585 is a memory corruption vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2026-74585?
How do I fix CVE-2026-74585?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-74585 being exploited?
There is no known exploitation of CVE-2026-74585 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74585, DEBIAN-CVE-2026-74585, GHSA-2wmm-p327-9hx6, UBUNTU-CVE-2026-74585.