Answer in brief
CVE-2026-55606 records a Medium severity (CVSS 6.5) vulnerability in odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp(). The current sources do not mark it as known exploited. The current feed maps openwrt/odhcpd (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps openwrt/odhcpd (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| openwrt/odhcpdgeneric | <=25.12 | = 25.12 |
Published upstream
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 23, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 23, 2026
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.
Quoted source text, attributed separately from HOL analysis.