# CVE-2026-23359: bpf: Fix stack-out-of-bounds write in devmap

> A stack-out-of-bounds write in the Linux kernel BPF devmap allows attackers with specific network configurations to cause memory corruption or crashes.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 25 Mar 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-80589, BELL-CVE-2026-23359, DEBIAN-CVE-2026-23359, GHSA-5m94-46x3-f942, ROOT-OS-DEBIAN-12-CVE-2026-23359, ROOT-OS-DEBIAN-13-CVE-2026-23359, ROOT-OS-UBUNTU-2204-CVE-2026-23359, ROOT-OS-UBUNTU-2404-CVE-2026-23359, UBUNTU-CVE-2026-23359

## What is CVE-2026-23359?

CVE-2026-23359 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Mar 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: Fix stack-out-of-bounds write in devmap

get_upper_ifindexes() iterates over all upper devices and writes their
indices into an array without checking bounds.

Also the callers assume that the max number of upper devices is
MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack,
but that assumption is not correct and the number of upper devices could
be larger than MAX_NEST_DEV (e.g., many macvlans), causing a
stack-out-of-bounds write.

Add a max parameter to get_upper_ifindexes() to avoid the issue.
When there are too many upper devices, return -EOVERFLOW and abort the
redirect.

To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with
an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS.
Then send a packet to the device to trigger the XDP redirect path.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-23359?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23359?

Apply the vendor's patch.

## Is CVE-2026-23359 being exploited?

There is no known exploitation of CVE-2026-23359 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23359 and fix it if it is affected.

What it is: CVE-2026-23359 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Mar 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-2026-23359 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-23359/ (Markdown: https://insights.sbomify.com/CVE-2026-23359/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23359
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23359
- OSV: https://osv.dev/vulnerability/CVE-2026-23359

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23359/
Summaries are generated and may contain mistakes; the official description above is the record.