# CVE-2026-93174: bpf: Copy per-CPU map value padding in copy_map_value_long()

> A local attacker can read stale heap memory from per-CPU BPF map padding, potentially exposing sensitive kernel data.

- **Severity:** Not scored
- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102455, BELL-CVE-2026-93174, DEBIAN-CVE-2026-93174, GHSA-2m7j-g554-hf69, UBUNTU-CVE-2026-93174

## What is CVE-2026-93174?

CVE-2026-93174 is a vulnerability in Linux, published on 17 Sep 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:

bpf: Copy per-CPU map value padding in copy_map_value_long()

In kernel, per-CPU map elements are stored with
round_up(map->value_size, 8) bytes. On UAPI lookup paths, it copies the
rounded size for each CPU into a temporary buffer.

However, copy_map_value_long() passes 'map->value_size' to
bpf_obj_memcpy(). When the map has special fields, bpf_obj_memcpy() copies
around those fields with memcpy(), and does not copy the tail padding
between 'map->value_size' and round_up(map->value_size, 8).

The temporary UAPI lookup buffers are allocated without __GFP_ZERO. As a
result, when the per-CPU map's value size is not equal to
round_up(map->value_size, 8), UAPI LOOKUP_ELEM and its variants can return
stale heap contents from that padding to user space. The same issue
applies to bpf_iter for per-CPU maps.

Pass round_up(map->value_size, 8) to bpf_obj_memcpy() from
copy_map_value_long(), so per-CPU maps both with and without special
fields copy the entire per-CPU slot. Remove the now redundant round_up()
from bpf_obj_memcpy()'s long_memcpy path.

## Which versions are affected by CVE-2026-93174?


## How do I fix CVE-2026-93174?

Apply the vendor's patch.

## Is CVE-2026-93174 being exploited?

There is no known exploitation of CVE-2026-93174 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93174 and fix it if it is affected.

What it is: CVE-2026-93174 is a vulnerability in Linux, published on 17 Sep 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-2026-93174 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-2026-93174/ (Markdown: https://insights.sbomify.com/CVE-2026-93174/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93174
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93174
- OSV: https://osv.dev/vulnerability/CVE-2026-93174

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93174/
Summaries are generated and may contain mistakes; the official description above is the record.