BusyBox DHCPv6 Client Heap Buffer Overflow via DNS_SERVERS
Summary
| CVE | CVE-2026-29004 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-04 18:16:26 UTC |
| Updated | 2026-07-15 02:19:20 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 7.2 HIGH from [email protected]
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.003750000 probability, percentile 0.295410000 (date 2026-07-03)
Problem Types: CWE-122 | CWE-131 | CWE-122 CWE-122: Heap-based Buffer Overflow | CWE-131 Incorrect Calculation of Buffer Size
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7.2 | HIGH | 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/E:X/C... |
| 4.0 | CNA | CVSS | 7.2 | HIGH | 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 |
| 3.1 | ADP | CVSS | 8.8 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | [email protected] | Secondary | 8.1 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 8.8 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 8.1 | HIGH | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
CVSS v4.0 Breakdown
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Vda-linux | Busybox Mirror | affected 42202bfb1e6ac51fa995beda8be4d7b654aeee2a git | Not specified |
| ADP | Red Hat | Red Hat Hardened Images | unaffected 1.37.0-7.3.hum1 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| busybox.net | [email protected] | busybox.net | |
| github.com/vda-linux/busybox_mirror/commit/d368f3f7836d1c2484c8f839316e5... | [email protected] | github.com | |
| github.com/vda-linux/busybox_mirror/commit/42202bfb1e6ac51fa995beda8be4d... | [email protected] | github.com | |
| access.redhat.com/errata/RHSA-2026:30652 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29004.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| www.vulncheck.com/advisories/busybox-dhcpv6-client-heap-buffer-overflow-via-dns... | [email protected] | www.vulncheck.com | |
| access.redhat.com/security/cve/CVE-2026-29004 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| y637f9qq2x.com/posts/busybox-dhcpv6-heap-overflow | [email protected] | y637f9qq2x.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. (en)
CNA: VulnCheck (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-05-04T19:03:24.638Z | Reported to Red Hat. |
| ADP | 2026-05-04T18:05:18.962Z | Made public. |
Solutions
ADP: RHSA-2026:30652: Red Hat Hardened Images
Workarounds
ADP: To mitigate this vulnerability, restrict network access to systems running BusyBox as a DHCPv6 client, ensuring that only trusted DHCPv6 servers can communicate with it. If the DHCPv6 client functionality is not essential for the system's operation, consider disabling the `udhcpc6` service or configuring it to only accept responses from known, trusted sources. Consult product-specific documentation for details on managing network services and configurations. Any changes to network service configurations may require a service restart to take effect, potentially impacting network connectivity.