# CVE-2026-68293: net/mlx5: Fix MCIA register buffer overflow on 32 dword reads

> A buffer overflow in the Linux kernel mlx5 driver allows local attackers to cause a system crash via ethtool EEPROM reads.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-95087, BELL-CVE-2026-68293, DEBIAN-CVE-2026-68293, GHSA-7555-mcj4-25r2, UBUNTU-CVE-2026-68293

## What is CVE-2026-68293?

CVE-2026-68293 is a high-severity memory corruption vulnerability in Linux, published on 10 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:

net/mlx5: Fix MCIA register buffer overflow on 32 dword reads

The MCIA register can return up to 32 dwords (128 bytes) when the device
advertises the mcia_32dwords capability, but struct
mlx5_ifc_mcia_reg_bits only defines dword_0..11, leaving room for just
12 dwords (48 bytes) of data.

mlx5_query_mcia() clamps the read size to mlx5_mcia_max_bytes() and then
memcpy()s that many bytes out of the register, potentially reading past
the end of the 'out' buffer. On kernels built with FORTIFY_SOURCE this
is caught as a buffer overflow while reading the module EEPROM via
ethtool:

  detected buffer overflow in memcpy
  kernel BUG at lib/string_helpers.c:1048!
  RIP: 0010:fortify_panic+0x13/0x20
  Call Trace:
   mlx5_query_mcia.isra.0+0x200/0x210 [mlx5_core]
   mlx5_query_module_eeprom_by_page+0x4a/0xa0 [mlx5_core]
   mlx5e_get_module_eeprom_by_page+0xbb/0x120 [mlx5_core]
   eeprom_prepare_data+0xf3/0x170
   ethnl_default_doit+0xf1/0x3b0

Extend the mcia_reg layout to 32 dwords.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-68293?


## How do I fix CVE-2026-68293?

Apply the vendor's patch.

## Is CVE-2026-68293 being exploited?

There is no known exploitation of CVE-2026-68293 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68293 and fix it if it is affected.

What it is: CVE-2026-68293 is a high-severity memory corruption vulnerability in Linux, published on 10 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-2026-68293 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-2026-68293/ (Markdown: https://insights.sbomify.com/CVE-2026-68293/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68293
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68293
- OSV: https://osv.dev/vulnerability/CVE-2026-68293

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68293/
Summaries are generated and may contain mistakes; the official description above is the record.