A vulnerability has been found in Yealink SIP-T46U 108.86.0.118. This affects the function mod_upgrade.SparePartsUpload of the file /api/upgrade/accupgradebychunk of the component Firmware Chunk Upload handler. Such manipulation of the argument uid leads to stack-based buffer overflow. The attack can only be initiated within the local network. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
Casky was already ahead
This CVE exploits attack patterns that Casky's 255matched 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-2026-12220 is a stack-based buffer overflow vulnerability in Yealink SIP-T46U IP phones affecting the firmware chunk upload handler. An attacker can exploit improper input validation on the 'uid' parameter in the /api/upgrade/accupgradebychunk endpoint to trigger memory corruption. While the attack requires local network access, this is a significant risk for organizations using Yealink phones in their VoIP infrastructure, as compromised phones can become persistent foothold devices for lateral movement within enterprise networks. The vulnerability's public disclosure and vendor non-response elevate urgency for affected organizations to assess their exposure and implement mitigations immediately.
Casky.ai's 255 matching security skills leverage Claude's extended reasoning to detect the adversarial techniques underlying this vulnerability. The platform maps to MITRE ATT&CK's Execution (TA0002) and Persistence (TA0003) tactics—analyzing how attackers use firmware manipulation to achieve code execution and maintain persistent access. Practitioners using Casky would identify suspicious patterns including: abnormal chunk upload requests with oversized uid parameters, unexpected memory access signatures during firmware operations, and unusual process behavior post-upload that indicates successful code execution. The platform's Claude-powered analysis correlates these indicators across your network to distinguish genuine firmware updates from exploitation attempts, providing actionable findings that connect low-level buffer overflow mechanics to enterprise attack chains.
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-2026-12220.
Casky has 255 skills that investigate the attack patterns behind CVE-2026-12220. Run one and get CVSS-scored findings in 3 minutes.
Run the skill that detects this →analyzing-browser-forensics-with-hindsight
digital forensics · low
analyzing-cobalt-strike-beacon-configuration
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correlating-security-events-in-qradar
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deobfuscating-javascript-malware
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detecting-container-drift-at-runtime
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detecting-container-escape-attempts
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detecting-container-escape-with-falco-rules
container security · low
detecting-dcsync-attack-in-active-directory
threat hunting · low
detecting-dll-sideloading-attacks
threat hunting · low
detecting-email-forwarding-rules-attack
threat hunting · low
detecting-evasion-techniques-in-endpoint-logs
endpoint security · low
detecting-fileless-attacks-on-endpoints
endpoint security · low
detecting-fileless-malware-techniques
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threat hunting · low
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detecting-kerberoasting-attacks
threat hunting · low
detecting-lateral-movement-with-splunk
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threat hunting · low
detecting-mimikatz-execution-patterns
threat hunting · low
detecting-ntlm-relay-with-event-correlation
threat hunting · low
detecting-pass-the-hash-attacks
threat hunting · low
detecting-privilege-escalation-attempts
threat hunting · low
detecting-privilege-escalation-in-kubernetes-pods
container security · low
detecting-process-hollowing-technique
threat hunting · low
detecting-process-injection-techniques
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detecting-rootkit-activity
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threat hunting · low
detecting-t1548-abuse-elevation-control-mechanism
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detecting-wmi-persistence
threat hunting · low
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red teaming · high
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red teaming · high
exploiting-nopac-cve-2021-42278-42287
red teaming · high
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exploiting-zerologon-vulnerability-cve-2020-1472
red teaming · high
extracting-browser-history-artifacts
digital forensics · low
extracting-config-from-agent-tesla-rat
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extracting-credentials-from-memory-dump
digital forensics · low
extracting-iocs-from-malware-samples
malware analysis · medium
extracting-windows-event-logs-artifacts
digital forensics · low
hardening-docker-containers-for-production
container security · low
hardening-docker-daemon-configuration
container security · low
hardening-linux-endpoint-with-cis-benchmark
endpoint security · low
hardening-windows-endpoint-with-cis-benchmark
endpoint security · 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
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hunting-for-dcom-lateral-movement
threat hunting · low
hunting-for-dcsync-attacks
threat hunting · low
hunting-for-defense-evasion-via-timestomping
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hunting-for-dns-based-persistence
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hunting-for-dns-tunneling-with-zeek
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hunting-for-domain-fronting-c2-traffic
threat hunting · low
hunting-for-lateral-movement-via-wmi
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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
threat hunting · low
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
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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
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implementing-memory-protection-with-dep-aslr
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implementing-opa-gatekeeper-for-policy-enforcement
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implementing-runtime-security-with-tetragon
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implementing-siem-use-cases-for-detection
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implementing-soar-automation-with-phantom
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implementing-soar-playbook-with-palo-alto-xsoar
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implementing-supply-chain-security-with-in-toto
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implementing-threat-modeling-with-mitre-attack
soc operations · low
implementing-ticketing-system-for-incidents
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implementing-usb-device-control-policy
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investigating-insider-threat-indicators
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investigating-phishing-email-incident
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digital forensics · low
performing-container-escape-detection
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performing-container-security-scanning-with-trivy
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performing-credential-access-with-lazagne
red teaming · high
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soc operations · low
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performing-dynamic-analysis-with-any-run
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performing-kerberoasting-attack
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performing-kubernetes-cis-benchmark-with-kube-bench
container security · low
performing-kubernetes-etcd-security-assessment
container security · low
performing-kubernetes-penetration-testing
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performing-lateral-movement-detection
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performing-lateral-movement-with-wmiexec
red teaming · high
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performing-malware-persistence-investigation
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performing-malware-triage-with-yara
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performing-memory-forensics-with-volatility3
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performing-mobile-device-forensics-with-cellebrite
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performing-network-forensics-with-wireshark
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performing-network-packet-capture-analysis
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performing-threat-hunting-with-yara-rules
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performing-timeline-reconstruction-with-plaso
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performing-user-behavior-analytics
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performing-vulnerability-scanning-with-nessus
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recovering-deleted-files-with-photorec
digital forensics · low
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reverse-engineering-dotnet-malware-with-dnspy
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reverse-engineering-malware-with-ghidra
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scanning-container-images-with-grype
container security · low
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container security · low
scanning-kubernetes-manifests-with-kubesec
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securing-container-registry-with-harbor
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securing-helm-chart-deployments
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triaging-security-alerts-in-splunk
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