CVE-2026-55606

odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()

MEDIUM
6.5
CVSS Score
Published: October 23, 2026 at 01:21 PM UTC
Updated: October 29, 2026 at 06:17 PM UTC
1 product affected across 1 vendorOdhcpd

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.5%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

<= 25.12

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-126

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