CVE-2026-55606

MEDIUM CVSS 6.5

Published: 2026-10-23

Modified: 2026-10-23

Enriched via mock

Tenable Plugin

Checking the public Tenable catalog…

AI Threat Summary

CVE-2026-55606 is a moderate vulnerability with a CVSS score of 6.5 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

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.

Attack Chain

Reconnaissance

Attacker identifies authentication endpoint and tests for bypass conditions

Initial Access

Attacker exploits CVE-2026-55606 authentication flaw to gain unauthorized access without valid credentials

Discovery

Attacker enumerates accessible resources, users, and configurations

Collection

Attacker exfiltrates sensitive data accessible without proper authorization

MITRE ATT&CK Techniques

T1078 Valid Accounts

Initial Access

Authentication bypass grants attacker access as legitimate user

T1548 Abuse Elevation Control Mechanism

Privilege Escalation

Bypassed auth may grant elevated or admin-level permissions

Indicators of Compromise

Type	Value	Description
user_agent	`Mozilla/5.0 (compatible; exploit/1.0)`	Generic exploit scanner user agent pattern
url	`/api/vuln-endpoint?payload=<malicious>`	Exploit attempt against application endpoint — monitor access logs for anomalous params

Remediation

1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.

Quick Facts

CVE ID	CVE-2026-55606
CVSS Score	6.5
Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L`
Published	2026-10-23
Exploited	No
CISA KEV	No
PoC	Not public

References

External Resources

NVD Entry BleepingComputer The Hacker News