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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.

PUBLISHED Reserved 2026-03-03 | Published 2026-05-04 | Updated 2026-05-06 | Assigner VulnCheck




HIGH: 7.2CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

HIGH: 8.1CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Problem types

CWE-122: Heap-based Buffer Overflow

Product status

Default status
affected

Any version before 42202bfb1e6ac51fa995beda8be4d7b654aeee2a
affected

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

VulnCheck finder

References

y637f9qq2x.com/posts/busybox-dhcpv6-heap-overflow/ technical-description exploit

github.com/...ommit/42202bfb1e6ac51fa995beda8be4d7b654aeee2a patch

github.com/...ommit/d368f3f7836d1c2484c8f839316e5c93e76d4409 patch

busybox.net/ product

www.vulncheck.com/...nt-heap-buffer-overflow-via-dns-servers third-party-advisory

cve.org (CVE-2026-29004)

nvd.nist.gov (CVE-2026-29004)

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