# CVE-2026-56114: dhcpcd Stack Out-of-Bounds Write in dhcp6_makemessage()

> Unauthenticated attackers can trigger a stack out-of-bounds write in dhcpcd via crafted DHCPv6 messages, potentially leading to code execution or crashes.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/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:** 23 Jun 2026
- **Updated:** 28 Jul 2026
- **Also known as:** ALPINE-CVE-2026-56114, AZL-90216, BELL-CVE-2026-56114, DEBIAN-CVE-2026-56114, GHSA-8q8g-fjv5-5h56, UBUNTU-CVE-2026-56114

## What is CVE-2026-56114?

CVE-2026-56114 is a medium-severity memory corruption vulnerability in NetworkConfiguration dhcpcd, published on 23 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

dhcpcd through 10.3.2, fixed in commit 2f00c7b, contains a one-byte stack out-of-bounds write vulnerability in dhcp6_makemessage() in src/dhcp6.c that allows unauthenticated same-link attackers to write beyond a fixed local buffer by serializing an oversized RFC6603 OPTION_PD_EXCLUDE option body. Attackers can send a crafted DHCPv6 ADVERTISE message containing an IA_PD IAPREFIX /0 with a valid OPTION_PD_EXCLUDE using an exclude prefix length of /121 through /128 to trigger the out-of-bounds write and potentially corrupt adjacent stack memory.

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

## Which versions are affected by CVE-2026-56114?

It affects 1 product.


Products: Dhcpcd Project Dhcpcd.

## How do I fix CVE-2026-56114?

Apply the vendor's patch.

## Is CVE-2026-56114 being exploited?

There is no known exploitation of CVE-2026-56114 in the wild and no public exploit code.

## Other vulnerabilities in NetworkConfiguration dhcpcd

- [CVE-2019-11577](https://insights.sbomify.com/CVE-2019-11577/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-1503](https://insights.sbomify.com/CVE-2016-1503/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-1504](https://insights.sbomify.com/CVE-2016-1504/): dhcpcd before 6.10.0 allows remote attackers to cause a denial of service (invalid read and crash) via vectors related to the option length. (high 7.5)
- [CVE-2026-56116](https://insights.sbomify.com/CVE-2026-56116/): dhcpcd Memory Leak DoS via IPv6 Router Advertisement Handling (high 7.1)
- [CVE-2014-7912](https://insights.sbomify.com/CVE-2014-7912/): Memory corruption in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56114 and fix it if it is affected.

What it is: CVE-2026-56114 is a medium-severity memory corruption vulnerability in NetworkConfiguration dhcpcd, published on 23 Jun 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-2026-56114 in the wild and no public exploit code.

Affected product: NetworkConfiguration dhcpcd. 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-2026-56114/ (Markdown: https://insights.sbomify.com/CVE-2026-56114/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56114
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56114
- OSV: https://osv.dev/vulnerability/CVE-2026-56114

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56114/
Summaries are generated and may contain mistakes; the official description above is the record.