dhcpcd Stack Out-of-Bounds Write in dhcp6_makemessage()
Key facts
- Attack vector
- Adjacent network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-787 and the CVSS impact.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| NetworkConfiguration | dhcpcd | up to 10.3.2 | — | Patch available | CNA |
- dhcpcd VendorNetworkConfiguration Affected up to 10.3.2 Fixed in — Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:dhcpcd_project:dhcpcd:*:*:*:*:*:*:*:* | up to 10.3.2 | Vulnerable | NetworkConfiguration |
- cpe:2.3:a:dhcpcd_project:dhcpcd:*:*:*:*:*:*:*:* Versions up to 10.3.2 Vulnerable ·NetworkConfiguration
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-56114
- 2026-10-03 Alias added: GHSA-8q8g-fjv5-5h56
References
More NetworkConfiguration Dhcpcd vulnerabilities
- TI-2019-08650 dhcpcd before 7.2.1 contains a buffer overflow in dhcp6_findna in dhcp6.c when reading NA/TA addresses. CVSS 3.0CRITICAL 9.8
- TI-2016-01390 dhcpcd before 6.10.0, as used in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x… CVSS 3.0CRITICAL 9.8
- TI-2019-08823 dhcp6.c in dhcpcd before 6.11.7 and 7.x before 7.2.2 has a buffer over-read in the D6_OPTION_PD_EXCLUDE feature. CVSS 3.1CRITICAL 9.8
- TI-2016-01391 dhcpcd before 6.10.0 allows remote attackers to cause a denial of service (invalid read… CVSS 3.0HIGH 7.5
- TI-2012-05402 The decode_search function in dhcp.c in dhcpcd 3.x does not properly free allocated… CVSS 3.0HIGH 7.5
- TI-2012-05401 The decode_search function in dhcp.c in dhcpcd 3.x allows remote DHCP servers to cause a… CVSS 3.0HIGH 7.5
Sources
- CVE-2026-56114 · CVE Program
- CVE-2026-56114 · NVD
- FIRST EPSS
- GHSA-8q8g-fjv5-5h56 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-56114 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences