Vulnerability in Openwrt Odhcpd
CVE-2026-55606
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. In versions 25.12 and prior, odhcpd's DHCPv6 self-loop detection at dhcpv6.c:720 uses a network-byte-order DUID length value directly as the memcmp() size parameter. On little-endian hosts, this causes memcmp() to read far beyond the stack buffer — a single unauthenticated DHCPv6 packet triggers a 2560-byte overread from a 128-byte buffer. At time of publication, there are no publicly available patches.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Openwrt Odhcpd — versions <= 25.12
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-55606?
- CVE-2026-55606 is a medium-severity vulnerability in Openwrt Odhcpd, classified under Buffer Over-read. CVSS score: 6.5/10. Published 2026-10-23.
- How severe is CVE-2026-55606?
- Medium severity. CVSS v3 base score is 6.5 out of 10.