CVE-2026-36609Public exploitNetwork attack vector

Plaintext password recovery via reversible session tokens

Published Jun 3, 2026 · Updated Jun 3, 2026

Password recovery in Mercusys AC12G (EU) V1 firmware AC12G(EU)_V1_200909 allows man-in-the-middle attackers to recover plaintext passwords. The securityEncode function applies reversible XOR encoding with fixed inputs while the router reuses a per-source-IP nonce throughout each boot cycle. Capturing one TDDP authentication exchange from the same source IP is sufficient for password recovery and session replay.

CVSS severity7.3
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Password recovery in Mercusys AC12G (EU) V1 firmware AC12G(EU)_V1_200909 allows man-in-the-middle attackers to recover plaintext passwords. The securityEncode function applies reversible XOR encoding with fixed inputs while the router reuses a per-source-IP nonce throughout each boot cycle. Capturing one TDDP authentication exchange from the same source IP is sufficient for password recovery and session replay.

The record

CVE
CVE-2026-36609
Published
Jun 3, 2026
Updated
Jun 3, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327, CWE-341, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm
CWE-341Predictable from Observable State
T1040Network Sniffing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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