# CVE-2026-56114: dhcpcd: dhcpcd through 10.3.2, fixed in commit 2f00c7b, contains a one-byte stack out-of-bounds write vulnerability in dhcp6_...

CVE-2026-56114 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-56114, released July 2, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-56114
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0027
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 23, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dhcpcd Debian 13.5 (trixie) | 1:10.1.0-11+deb13u3 | [DEBIAN-CVE-2026-56114](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56114.md) | Jul 2, 2026 |
| Linux | dhcpcd Debian 14 | 1:10.3.2-4 | [DEBIAN-CVE-2026-56114](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56114.md) | Jul 2, 2026 |
| Linux | dhcpcd5 Debian 12.15 (bookworm) | 9.4.1-24~deb12u5 | [DEBIAN-CVE-2026-56114](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56114.md) | Jul 2, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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