CVE-2026-36609 — HIGH (7.3)

Vulnerability Description

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 uses a static authentication nonce that does not change between requests from the same source IP. Combined with the predictable XOR-based password encoding (securityEncode function), this allows an attacker to reverse captured authentication tokens to recover the plaintext password.

CVSS Score

7.3

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

LOW

Integrity

LOW

Availability

LOW

Related Weaknesses (CWE)

CWE-327 CWE-341

References

https://github.com/Tymbark7372/MERCUSYS-AC12G/blob/master/advisories/CVE-2026-36

FAQ

What is CVE-2026-36609?

CVE-2026-36609 is a vulnerability with a CVSS score of 7.3 (HIGH). Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 uses a static authentication nonce that does not change between requests from the same source IP. Combined with the predictable XOR-base...

How severe is CVE-2026-36609?

CVE-2026-36609 has been rated HIGH with a CVSS base score of 7.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-36609?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.