Varonis Threat Labs disclosed CoSnitch on August 18, 2026, the same day Microsoft shipped the fix. Researcher Lior Adar reported the vulnerability chain to Microsoft in December 2025. The disclosure came nearly eight months later. CoSnitch chains three separate weaknesses in Microsoft Copilot Personal, the consumer AI assistant hosted at copilot.microsoft.com. The first weakness is automatic prompt execution: the standard ?q= URL parameter for pre-populating a Copilot query can be combined with a second, undocumented parameter, which Varonis identifies as ?autorun=1 in its technical write-up, to cause Copilot to execute the embedded prompt instantly when the page loads rather than waiting for the user to press Enter. An attacker sends a victim a link that looks like a normal Copilot URL. When the victim clicks the link and Copilot loads, the attacker's prompt fires automatically in the context of the victim's authenticated session. The second weakness is OAuth-scoped data access: Copilot Personal can be connected to Gmail, Google Drive, Google Calendar, and other services through OAuth integrations. A prompt running in the victim's authenticated session can read data from any of those connected sources as if the user had asked Copilot to retrieve it. The third weakness is the exfiltration path: Copilot has a capability to fetch and summarize external URLs. An attacker-controlled prompt can gather data from connected accounts into the model's active context, encode it for URL transport, and instruct Copilot to request an attacker-controlled URL containing the encoded information. The response, including email content, calendar entries, file metadata, chat history, and persistent memory contents, arrives at the attacker's server through what appears to be a routine Copilot summarization request. Varonis confirmed that the entire attack chain produces no process, file, network connection, or log entry that standard security tooling would flag as anomalous. The exfiltration is indistinguishable from normal Copilot behavior. Microsoft assigned CVSS 8.8, rated it a critical information disclosure vulnerability, and noted no customer action is required following the August 18 patch. Enterprise customers using Microsoft 365 Copilot are unaffected. The scope is limited to Copilot Personal. Varonis confirmed no evidence of exploitation in the wild before the patch.

GuidePoint Security's Research and Intelligence Team published analysis on August 18 of a threat actor operating as Ransom Busters LTD. The group targets organizations that have suffered ransomware attacks by sending unsolicited emails to CEOs or IT leaders before the attacks become public. The emails claim that Ransom Busters has discovered the victim's stolen data on ransomware servers, has accessed the encryption key storage of the attacking ransomware group, and can delete the exfiltrated data while also providing decryption keys, offering the service for $20,000 to $60,000. GuidePoint observed this activity during incident response engagements for attacks linked to DragonForce, Settra, and Anubis ransomware operations. During engagement with the actor, GuidePoint confirmed that Ransom Busters possessed the same stolen datasets held by the ransomware affiliate responsible for each intrusion. The group claims to have exploited vulnerabilities in the administrative panels of ransomware-as-a-service operations, giving it access to victim data, encryption keys, and infrastructure controls. GRIT assesses with moderate confidence that Ransom Busters is actually a ransomware affiliate, likely operating across multiple RaaS operations, attempting to divert extortion payments from the primary ransomware group by offering a parallel payment path. The group also overlaps in tooling with broader campaigns, using SoftPerfect Network Scanner and s5cmd, tools consistent with ransomware affiliate tradecraft. The pre-disclosure contact is the most operationally concerning detail: it implies either insider access to ransomware group communications, active participation in the initial attack, or direct access to the RaaS panel that the group claims to have compromised. GuidePoint notes that any unauthorized access to a ransomware group's servers, even with the stated intent of helping victims, may constitute a violation of the Computer Fraud and Abuse Act.

Four days after Microsoft's August 2026 Patch Tuesday, the researcher known as Nightmare Eclipse published ShieldBreak, a new zero-day in Microsoft Defender tracked as CVE-2026-69414. ShieldBreak is a patch bypass for RoguePlanet, CVE-2026-50656, a Microsoft Defender privilege-escalation vulnerability that Microsoft patched in a prior release with a CVSS score of 7.8. A patch bypass means that Microsoft's original fix for RoguePlanet did not fully close the underlying vulnerability, and Nightmare Eclipse found a variant of the same attack path that the patch did not address. ShieldBreak lets a local attacker with low privileges escalate to NT AUTHORITY\SYSTEM, the highest level of access on a Windows system, on Windows 10, Windows 11, and Windows Server including the current Server 2025 release. A public proof-of-concept is available. Technical write-ups at the time of disclosure described a 100% success rate against fully patched test systems, with later reporting noting variability between machines on specific configurations. No exploitation in the wild has been confirmed. Microsoft is investigating and has not yet published a patch or a scheduled patch date. Nightmare Eclipse is the same researcher responsible for the LegacyHive series covered in this brief from Issue 88 through Issue 106. CVE-2026-62832, the User Profile Service elevation-of-privilege flaw from that series, sat for 24 days without a patch before Microsoft closed it in August Patch Tuesday. Three prior disclosures in the same series were exploited before their patches arrived.