# CVE-2026-74274: cxl/region: Fill first free targets[] slot during auto-discovery

> A null pointer dereference in the Linux kernel CXL driver allows local attackers to cause a system crash via general protection faults.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-74274, GHSA-xw27-v9cq-fc4v, UBUNTU-CVE-2026-74274

## What is CVE-2026-74274?

CVE-2026-74274 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

cxl/region: Fill first free targets[] slot during auto-discovery

Any invalid endpoint decoder pointer in the target array of an active
region is not allowed by cxl driver. This means cxl driver always
assumes the first p->nr_targets entries of the target array in an
auto-assembly region are valid. However, there are scenarios that could
leave NULL endpoint decoder pointer holes in the target array.

1. When cxl_cancel_auto_attach() removes an endpoint decoder from a
   target array, the target slot is set to NULL. If the removed endpoint
   decoder is not the last element in the target array, the target array
   will contain a NULL hole.

2. When a auto-assembly region removes an assigned endpoint decoder, if
   the removed endpoint decoder is not the last element in the target
   array, always remains a NULL hole in the target array.

When a NULL pointer hole exists in a region's target array, it
introduces two potential problems:
1. Access an endpoint decoder via a NULL pointer. it always trigger
   calltrace like that.
    Oops: general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] SMP KASAN PTI
    RIP: 0010:cxl_calc_interleave_pos+0x26/0x810 [cxl_core]
    Call Trace:
      <TASK>
      cxl_region_attach+0xc50/0x2140 [cxl_core]
      cxl_add_to_region+0x321/0x2330 [cxl_core]
      discover_region+0x92/0x150 [cxl_port]
      device_for_each_child+0xf3/0x170
      cxl_port_probe+0x150/0x200 [cxl_port]
      cxl_bus_probe+0x4f/0xa0 [cxl_core]
      really_probe+0x1c8/0x960
      __driver_probe_device+0x323/0x450
      driver_probe_device+0x45/0x120
      __device_attach_driver+0x15d/0x280
      bus_for_each_drv+0x10f/0x190

2. Not having enough valid endpoint decoders attached to an
   auto-assembly region. if an auto-assembly region is created with lock
   flag or assigned endpoint decoder with lock flag, which means
   assigned endpoint decoder will not be reset during detaching, they
   could re-attach to the auto-assembly region again. But cxl region
   driver relies on p->nr_targets to verify whether the required number
   of endpoint decoders has been attached, and NULL endpoint decoder
   pointers are still counted in that case.

To fix above issues, adjust cxl_region_attach_auto() logic to find the
first free target slot for endpoint decoder attachment, this ensures
NULL holes in the target array are filled, rather than adding new
endpoint decoders at the tail of the target array.

## Which versions are affected by CVE-2026-74274?


## How do I fix CVE-2026-74274?

Apply the vendor's patch.

## Is CVE-2026-74274 being exploited?

There is no known exploitation of CVE-2026-74274 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74274 and fix it if it is affected.

What it is: CVE-2026-74274 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74274 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74274/ (Markdown: https://insights.sbomify.com/CVE-2026-74274/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74274
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74274
- OSV: https://osv.dev/vulnerability/CVE-2026-74274

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74274/
Summaries are generated and may contain mistakes; the official description above is the record.