# CVE-2026-29004: BusyBox DHCPv6 Client Heap Buffer Overflow via DNS_SERVERS

> Network-adjacent attackers can trigger heap buffer overflow in BusyBox DHCPv6 client via crafted responses, leading to code execution or denial of service on embedded systems.

- **Severity:** High 7.2 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **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:** 4 May 2026
- **Updated:** 15 Jul 2026
- **Also known as:** BELL-CVE-2026-29004, DEBIAN-CVE-2026-29004, ECHO-4d14-5e51-2c9b, GHSA-vx55-mmvv-p227, OESA-2026-2357, RHSA-2026:30652, SUSE-SU-2026:2053-1, SUSE-SU-2026:2054-1, SUSE-SU-2026:2069-1, SUSE-SU-2026:21943-1, SUSE-SU-2026:22020-1, SUSE-SU-2026:2204-1, UBUNTU-CVE-2026-29004, openSUSE-SU-2026:10740-1, openSUSE-SU-2026:20883-1

## What is CVE-2026-29004?

CVE-2026-29004 is a high-severity memory corruption vulnerability in vda-linux busybox_mirror, published on 4 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

BusyBox before commit 42202bf contains a heap buffer overflow vulnerability in the DHCPv6 client (udhcpc6) DNS_SERVERS option handler in networking/udhcp/d6_dhcpc.c that allows network-adjacent attackers to trigger memory corruption by sending a crafted DHCPv6 response with a malformed D6_OPT_DNS_SERVERS option. Attackers can exploit incorrect heap buffer allocation calculations in the option_to_env() function to cause denial of service or achieve arbitrary code execution on embedded systems without heap hardening.

Weakness: CWE-131 (Incorrect Calculation of Buffer Size), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-29004?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `busybox` | Red Hat:hummingbird:1 | All versions | 0:1.37.0-7.3.hum1 |
| `busybox-petitboot` | Red Hat:hummingbird:1 | All versions | 0:1.37.0-7.3.hum1 |
| `busybox-shared` | Red Hat:hummingbird:1 | All versions | 0:1.37.0-7.3.hum1 |
| `busybox` | SUSE:Linux Enterprise Server 16.0 | All versions | 1.37.0-160000.6.1 |
| `busybox` | SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 1.37.0-160000.6.1 |
| `busybox` | openSUSE:Tumbleweed | All versions | 1.37.0-11.1 |

## How do I fix CVE-2026-29004?

Apply the vendor's patch.

## Is CVE-2026-29004 being exploited?

There is no known exploitation of CVE-2026-29004 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29004 and fix it if it is affected.

What it is: CVE-2026-29004 is a high-severity memory corruption vulnerability in vda-linux busybox_mirror, published on 4 May 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-2026-29004 in the wild and no public exploit code.

Affected product: vda-linux busybox_mirror. 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-2026-29004/ (Markdown: https://insights.sbomify.com/CVE-2026-29004/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29004
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29004
- OSV: https://osv.dev/vulnerability/CVE-2026-29004

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29004/
Summaries are generated and may contain mistakes; the official description above is the record.