CVE-2026-55606: medium-severity vulnerability in openwrt odhcpd
odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()
Published
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.5epss 0.4%
exploitation probability
0.4%top 68% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Affected products
openwrt · odhcpdRelated CVEs — openwrt odhcpd
In the same product, most dangerous first.
CVE-2026-53921CRITICALodhcpd: Stack buffer overflow in DHCPv6 IA reply serialization (2 independent sites)EPSS 1.1%CVE-2026-53922MEDIUModhcpd: pre-auth remote DoS via size_t underflow in dhcpv6_ia_handle_IAs (stack BOF, canary-terminated)EPSS 0.6%CVE-2026-53918HIGHodhcpd DHCPv6 IA dangling first pointer use-after-freeEPSS 0.5%CVE-2026-53920HIGHodhcpd DHCPv6 Short IA_NA/IA_PD Body Stack DisclosureEPSS 0.4%