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Vulnerability record · CVE-2026-29004 · published 4 May 2026

CVE-2026-29004: Heap-based buffer overflow vulnerability

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.

7.2 CVSS 4.0 High EPSS 0.62% · top 52.4% CWE-122 · Heap-based buffer overflowCWE-131 · CWE-131 Awaiting Analysis
7.2CVSS 4.0 base score
0.62%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
9References
15 Jul 2026Last modified by NVD

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.

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:

References

LinkTags
https://busybox.net/
https://github.com/vda-linux/busybox_mirror/commit/42202bfb1e6ac51fa995beda8be4d7b654aeee2a
https://github.com/vda-linux/busybox_mirror/commit/d368f3f7836d1c2484c8f839316e5c93e76d4409
https://www.vulncheck.com/advisories/busybox-dhcpv6-client-heap-buffer-overflow-via-dns-servers
https://y637f9qq2x.com/posts/busybox-dhcpv6-heap-overflow/
https://access.redhat.com/errata/RHSA-2026:30652
https://access.redhat.com/security/cve/CVE-2026-29004
https://bugzilla.redhat.com/show_bug.cgi?id=2466526
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29004.json

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Source: NIST National Vulnerability Database (record CVE-2026-29004), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.