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.
Casky was already ahead
This CVE exploits attack patterns that Casky's 282matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.
CVE-2026-36609 affects Mercusys AC12G (EU) V1 routers running firmware version AC12G(EU)_V1_200909, introducing a critical authentication bypass vulnerability. The vulnerability stems from two compounding weaknesses: a static authentication nonce that remains constant for requests from the same source IP, combined with a predictable XOR-based password encoding scheme in the securityEncode function. This allows attackers to capture authentication tokens, reverse-engineer the encoding through cryptanalysis, and recover plaintext administrator credentials. With a CVSS score of 7.3, this vulnerability is particularly dangerous for home and small office networks that typically rely on default or weak credentials, giving attackers direct access to device configuration, network traffic interception, and lateral movement capabilities.
Casky's 282 matching skills leverage Claude AI with extended reasoning to detect the attack patterns underlying this vulnerability across MITRE ATT&CK techniques TA0010 (Exfiltration) and TA0011 (Command and Control). Practitioners using Casky would identify suspicious patterns including: repeated authentication requests from the same source IP with identical nonce values (indicating static token generation), captured HTTP traffic containing XOR-encoded credentials with consistent byte patterns (revealing the predictable encoding), and failed credential brute-force attempts that suddenly succeed after token analysis. The platform's skills would flag CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) and CWE-341 (Predictable from External Input) violations, alerting security teams to weak cryptographic implementations and enabling them to correlate these findings with network reconnaissance activity and subsequent command-and-control communications that would follow successful credential theft.
Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →
These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-36609.
Casky has 282 skills that investigate the attack patterns behind CVE-2026-36609. Run one and get CVSS-scored findings in 3 minutes.
Run the skill that detects this →analyzing-bootkit-and-rootkit-samples
malware analysis · medium
analyzing-browser-forensics-with-hindsight
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analyzing-cobaltstrike-malleable-c2-profiles
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threat intelligence · low
analyzing-disk-image-with-autopsy
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analyzing-dns-logs-for-exfiltration
soc operations · low
analyzing-docker-container-forensics
digital forensics · low
analyzing-email-headers-for-phishing-investigation
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analyzing-golang-malware-with-ghidra
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analyzing-linux-system-artifacts
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analyzing-windows-event-logs-in-splunk
soc operations · low
analyzing-windows-lnk-files-for-artifacts
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analyzing-windows-prefetch-with-python
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analyzing-windows-registry-for-artifacts
digital forensics · low
analyzing-windows-shellbag-artifacts
digital forensics · low
auditing-tls-certificate-transparency-logs
threat intelligence · low
automating-ioc-enrichment
threat intelligence · low
building-adversary-infrastructure-tracking-system
threat intelligence · low
building-attack-pattern-library-from-cti-reports
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building-automated-malware-submission-pipeline
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building-c2-infrastructure-with-sliver-framework
red teaming · high
building-detection-rule-with-splunk-spl
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building-detection-rules-with-sigma
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building-incident-response-dashboard
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building-soc-metrics-and-kpi-tracking
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building-soc-playbook-for-ransomware
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building-threat-actor-profile-from-osint
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building-threat-feed-aggregation-with-misp
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threat intelligence · low
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collecting-open-source-intelligence
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collecting-threat-intelligence-with-misp
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conducting-domain-persistence-with-dcsync
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red teaming · high
conducting-internal-reconnaissance-with-bloodhound-ce
red teaming · high
conducting-man-in-the-middle-attack-simulation
network security · medium
conducting-pass-the-ticket-attack
red teaming · high
conducting-social-engineering-pretext-call
red teaming · high
conducting-spearphishing-simulation-campaign
red teaming · high
configuring-network-segmentation-with-vlans
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configuring-pfsense-firewall-rules
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configuring-snort-ids-for-intrusion-detection
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configuring-suricata-for-network-monitoring
network security · medium
correlating-security-events-in-qradar
soc operations · low
correlating-threat-campaigns
threat intelligence · low
deobfuscating-javascript-malware
malware analysis · medium
deobfuscating-powershell-obfuscated-malware
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detecting-arp-poisoning-in-network-traffic
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detecting-command-and-control-over-dns
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threat hunting · low
detecting-dll-sideloading-attacks
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detecting-dns-exfiltration-with-dns-query-analysis
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detecting-email-forwarding-rules-attack
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detecting-exfiltration-over-dns-with-zeek
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detecting-mimikatz-execution-patterns
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detecting-network-anomalies-with-zeek
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detecting-ntlm-relay-with-event-correlation
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detecting-pass-the-hash-attacks
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detecting-port-scanning-with-fail2ban
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threat hunting · low
detecting-process-hollowing-technique
threat hunting · low
detecting-process-injection-techniques
malware analysis · medium
detecting-rootkit-activity
malware analysis · medium
detecting-service-account-abuse
threat hunting · low
detecting-suspicious-powershell-execution
threat hunting · low
detecting-t1003-credential-dumping-with-edr
threat hunting · low
detecting-t1055-process-injection-with-sysmon
threat hunting · low
detecting-t1548-abuse-elevation-control-mechanism
threat hunting · low
detecting-wmi-persistence
threat hunting · low
evaluating-threat-intelligence-platforms
threat intelligence · low
executing-red-team-engagement-planning
red teaming · high
exploiting-active-directory-certificate-services-esc1
red teaming · high
exploiting-active-directory-with-bloodhound
red teaming · high
exploiting-bgp-hijacking-vulnerabilities
network security · medium
exploiting-constrained-delegation-abuse
red teaming · high
exploiting-ipv6-vulnerabilities
network security · medium
exploiting-kerberoasting-with-impacket
red teaming · high
exploiting-ms17-010-eternalblue-vulnerability
red teaming · high
exploiting-nopac-cve-2021-42278-42287
red teaming · high
exploiting-smb-vulnerabilities-with-metasploit
network security · medium
exploiting-zerologon-vulnerability-cve-2020-1472
red teaming · high
extracting-browser-history-artifacts
digital forensics · low
extracting-config-from-agent-tesla-rat
malware analysis · medium
extracting-credentials-from-memory-dump
digital forensics · low
extracting-iocs-from-malware-samples
malware analysis · medium
extracting-windows-event-logs-artifacts
digital forensics · low
generating-threat-intelligence-reports
threat intelligence · low
hunting-advanced-persistent-threats
threat intelligence · low
hunting-for-anomalous-powershell-execution
threat hunting · low
hunting-for-beaconing-with-frequency-analysis
threat hunting · low
hunting-for-cobalt-strike-beacons
threat hunting · low
hunting-for-command-and-control-beaconing
threat hunting · low
hunting-for-data-exfiltration-indicators
threat hunting · low
hunting-for-data-staging-before-exfiltration
threat hunting · low
hunting-for-dcom-lateral-movement
threat hunting · low
hunting-for-dcsync-attacks
threat hunting · low
hunting-for-defense-evasion-via-timestomping
threat hunting · low
hunting-for-dns-based-persistence
threat hunting · low
hunting-for-dns-tunneling-with-zeek
threat hunting · low
hunting-for-domain-fronting-c2-traffic
threat hunting · low
hunting-for-lateral-movement-via-wmi
threat hunting · low
hunting-for-living-off-the-cloud-techniques
threat hunting · low
hunting-for-living-off-the-land-binaries
threat hunting · low
hunting-for-lolbins-execution-in-endpoint-logs
threat hunting · low
hunting-for-ntlm-relay-attacks
threat hunting · low
hunting-for-persistence-mechanisms-in-windows
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hunting-for-persistence-via-wmi-subscriptions
threat hunting · low
hunting-for-process-injection-techniques
threat hunting · low
hunting-for-registry-persistence-mechanisms
threat hunting · low
hunting-for-registry-run-key-persistence
threat hunting · low
hunting-for-scheduled-task-persistence
threat hunting · low
hunting-for-shadow-copy-deletion
threat hunting · low
hunting-for-spearphishing-indicators
threat hunting · low
hunting-for-startup-folder-persistence
threat hunting · low
hunting-for-supply-chain-compromise
threat hunting · low
hunting-for-suspicious-scheduled-tasks
threat hunting · low
hunting-for-t1098-account-manipulation
threat hunting · low
hunting-for-unusual-network-connections
threat hunting · low
hunting-for-unusual-service-installations
threat hunting · low
hunting-for-webshell-activity
threat hunting · low
implementing-alert-fatigue-reduction
soc operations · low
implementing-bgp-security-with-rpki
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implementing-browser-isolation-for-zero-trust
network security · medium
implementing-ddos-mitigation-with-cloudflare
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implementing-network-access-control
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implementing-security-information-sharing-with-stix2
threat intelligence · low
implementing-siem-use-cases-for-detection
soc operations · low
implementing-soar-automation-with-phantom
soc operations · low
implementing-soar-playbook-with-palo-alto-xsoar
soc operations · low
implementing-stix-taxii-feed-integration
threat intelligence · low
implementing-taxii-server-with-opentaxii
threat intelligence · low
implementing-threat-intelligence-lifecycle-management
threat intelligence · low
implementing-threat-modeling-with-mitre-attack
soc operations · low
implementing-ticketing-system-for-incidents
soc operations · low
investigating-insider-threat-indicators
soc operations · low
investigating-phishing-email-incident
soc operations · low
investigating-ransomware-attack-artifacts
digital forensics · low
managing-intelligence-lifecycle
threat intelligence · low
mapping-mitre-attack-techniques
threat intelligence · low
monitoring-darkweb-sources
threat intelligence · low
performing-active-directory-bloodhound-analysis
red teaming · high
performing-ai-driven-osint-correlation
threat intelligence · low
performing-alert-triage-with-elastic-siem
soc operations · low
performing-arp-spoofing-attack-simulation
network security · medium
performing-automated-malware-analysis-with-cape
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performing-bandwidth-throttling-attack-simulation
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performing-cloud-forensics-investigation
digital forensics · low
performing-cloud-storage-forensic-acquisition
digital forensics · low
performing-credential-access-with-lazagne
red teaming · high
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threat intelligence · low
performing-deception-technology-deployment
soc operations · low
performing-dns-enumeration-and-zone-transfer
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performing-dynamic-analysis-with-any-run
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performing-file-carving-with-foremost
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performing-firmware-malware-analysis
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performing-indicator-lifecycle-management
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performing-initial-access-with-evilginx3
red teaming · high
performing-ioc-enrichment-automation
soc operations · low
performing-ip-reputation-analysis-with-shodan
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performing-kerberoasting-attack
red teaming · high
performing-lateral-movement-detection
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performing-lateral-movement-with-wmiexec
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performing-linux-log-forensics-investigation
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performing-log-analysis-for-forensic-investigation
digital forensics · low
performing-log-source-onboarding-in-siem
soc operations · low
performing-malware-hash-enrichment-with-virustotal
threat intelligence · low
performing-malware-ioc-extraction
threat intelligence · low
performing-malware-persistence-investigation
digital forensics · low
performing-malware-triage-with-yara
malware analysis · medium
performing-memory-forensics-with-volatility3
digital forensics · low
performing-memory-forensics-with-volatility3-plugins
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performing-mobile-device-forensics-with-cellebrite
digital forensics · low
performing-network-forensics-with-wireshark
digital forensics · low
performing-network-packet-capture-analysis
digital forensics · low
performing-network-traffic-analysis-with-tshark
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performing-network-traffic-analysis-with-zeek
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performing-open-source-intelligence-gathering
red teaming · high
performing-osint-with-spiderfoot
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performing-packet-injection-attack
network security · medium
performing-paste-site-monitoring-for-credentials
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performing-physical-intrusion-assessment
red teaming · high
performing-privilege-escalation-on-linux
red teaming · high
performing-purple-team-exercise
soc operations · low
performing-soc-tabletop-exercise
soc operations · low
performing-sqlite-database-forensics
digital forensics · low
performing-ssl-stripping-attack
network security · medium
performing-ssl-tls-inspection-configuration
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performing-ssl-tls-security-assessment
network security · medium
performing-static-malware-analysis-with-pe-studio
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performing-steganography-detection
digital forensics · low
performing-threat-emulation-with-atomic-red-team
threat intelligence · low
performing-threat-hunting-with-elastic-siem
soc operations · low
performing-threat-hunting-with-yara-rules
threat hunting · low
performing-threat-intelligence-sharing-with-misp
threat intelligence · low
performing-threat-landscape-assessment-for-sector
threat intelligence · low
performing-timeline-reconstruction-with-plaso
digital forensics · low
performing-user-behavior-analytics
soc operations · low
performing-vlan-hopping-attack
network security · medium
performing-wifi-password-cracking-with-aircrack
network security · medium
performing-windows-artifact-analysis-with-eric-zimmerman-tools
digital forensics · low
performing-wireless-security-assessment-with-kismet
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performing-yara-rule-development-for-detection
malware analysis · medium
processing-stix-taxii-feeds
threat intelligence · low
profiling-threat-actor-groups
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recovering-deleted-files-with-photorec
digital forensics · low
reverse-engineering-android-malware-with-jadx
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reverse-engineering-dotnet-malware-with-dnspy
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reverse-engineering-malware-with-ghidra
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reverse-engineering-ransomware-encryption-routine
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scanning-network-with-nmap-advanced
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tracking-threat-actor-infrastructure
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triaging-security-alerts-in-splunk
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