EUVD-2026-25310
GHSA-q6x5-8v4h-crwr
Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Remote, unauthenticated, low-complexity open redirect requiring a victim click (UI:R); it crosses trust boundaries (S:C) enabling token/privilege theft (C:H/I:H) with no availability impact.
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
4DescriptionCVE.org
Url redirection to untrusted site ('open redirect') in M365 Copilot allows an unauthorized attacker to elevate privileges over a network.
AnalysisAI
Privilege elevation in Microsoft 365 Copilot via an open redirect (CWE-601) lets an unauthenticated remote attacker abuse the AI assistant's URL-handling to bounce a victim to an attacker-controlled site and elevate privileges over the network. Rated CVSS 9.3 with a scope-changed vector because the redirect crosses a trust boundary, though exploitation requires the victim to interact (click) with the crafted link. No public exploit identified at time of analysis and EPSS is very low (0.04%), indicating no observed real-world exploitation despite the high severity score.
Technical ContextAI
The affected component is Microsoft 365 Copilot (cpe:2.3:a:microsoft:microsoft_365_copilot), the LLM-based productivity assistant embedded across the Microsoft 365 suite. The root cause is CWE-601 (URL Redirection to Untrusted Site / 'open redirect'): Copilot accepts or generates a redirect target without properly validating that the destination belongs to a trusted domain, allowing an attacker to craft a link that appears to originate from a legitimate Microsoft/Copilot context but forwards the user elsewhere. In an AI-assistant context this is more dangerous than a classic open redirect because the redirect can be leveraged to steal session tokens or OAuth/consent grants, producing the privilege-elevation impact reflected by the scope-changed CVSS vector (S:C).
RemediationAI
Patch available per vendor advisory - Microsoft has released a fix, and because Microsoft 365 Copilot is a cloud-hosted service the correction is applied server-side by Microsoft, so no exact customer-installable version number is published; confirm mitigation status via the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33102. As compensating controls while validating remediation, train users not to click unexpected Copilot-generated or Copilot-delivered links and to verify final destination domains, enforce phishing-resistant MFA and conditional-access policies to blunt any token/consent theft that a redirect enables, and consider tightening OAuth app-consent policies so a redirected user cannot silently grant elevated permissions (trade-off: stricter consent settings may block legitimate add-in workflows and increase admin approval overhead). Corroborating advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-33102.
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