Medium severity · published Oct 23, 2026
CVE-2026-55606
odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()
New
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OD
odhcpd · openwrt
<= 25.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55606
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55606
github.com
https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f
github.com
https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301
github.com
https://github.com/openwrt/odhcpd/pull/401
github.com
https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45
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