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CVE-2026-53146
thunderbolt: Limit XDomain response copy to actual frame size
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem drivers/thunderbolt. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53146 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
tb_xdomain_copy() copies req->response_size bytes from the received packet buffer regardless of the actual frame size. When a short response arrives, this reads past the valid frame data in the DMA pool buffer into stale contents from previous transactions. Use the minimum of frame size and expected response size for the copy length.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/thunderbolt/xdomain.c
- What this is
- THUNDERBOLT DRIVERMAINTAINERS section matched on drivers/thunderbolt/ · linux-usb@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-06-25 (4 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:Nsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.26%, higher than 16.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/thunderbolt
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.15 | 5.10.259 | c55da494dfb4 |
| 4.15 | 5.15.210 | 7720654b4842 |
| 4.15 | 6.1.176 | 033dfa63bf6b |
| 4.15 | 6.6.143 | fc261397295b |
| 4.15 | 6.12.94 | a15b6d3136ac |
| 4.15 | 6.18.36 | b5daa920f44c |
| 4.15 | 7.0.13 | b2c1e5d9f159 |
| 4.15 | 7.1 | 4db2bd2ed478 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- Exploitation requires a malicious peer on the same Thunderbolt/USB4 XDomain fabric to send crafted control-channel responses. This is not internet-routable, but it is reachable over the adjacent local interconnect once the peer is connected.
- AC:LAttack complexity, low
- The attacker can reply to automatic XDomain handshake requests with a short, CRC-valid response matching the observed route and protocol UUID. No race or external timing condition is required.
- PR:NPrivileges required, none
- The attacker is the external XDomain peer and does not need credentials or privileges on the victim Linux system. The module parameter and ACPI allowance are deployment gates, not attacker privilege checks.
- UI:NUser interaction, none
- After the malicious peer is present on the Thunderbolt/USB4 link, XDomain discovery runs automatically. No victim user action is required to trigger the vulnerable copy.
- S:UScope, unchanged
- The vulnerable code and impacts are within the victim kernel/Thunderbolt domain. This does not cross a VM, IOMMU, or separate security authority boundary.
- C:HConfidentiality impact, high
- The bug is an out-of-bounds source read from the Thunderbolt control DMA frame buffer into kernel response objects, exposing stale contents from previous transactions. Because the over-read is not limited to only a few bytes and can influence/reflection paths such as XDomain UUID/properties handling, confidentiality is High.
- I:LIntegrity impact, low
- Stale bytes copied into trusted XDomain response structures can alter limited kernel protocol state such as peer identity, route, link status, or advertised properties. There is no direct arbitrary write or control-flow corruption from this fix alone.
- A:NAvailability impact, none
- The copy destination is sized for the expected response, and the over-read stays within the DMA frame allocation rather than causing an immediate kernel crash. A malicious peer can disrupt its own XDomain handshake, but this bug does not create a distinct system availability impact.