CVE-2026-55606 odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-55606?
CVE-2026-55606 is a medium-severity vulnerability in openwrt odhcpd, published on 23 Oct 2026.
Official 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.
Weakness: CWE-126
Which versions are affected by CVE-2026-55606?
How do I fix CVE-2026-55606?
No fix has been published for CVE-2026-55606 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-55606 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55606 exists.
Sources
Also known as GHSA-x8x4-7gvf-gp45.