Disclosed vulnerability
CVE-2026-80098: improper cryptographic signature verification in Copilot Studio allows privilege elevation
AIR-2026-0227 AIR record · 2026-09-microsoft-copilot-studio-signature-eop
From the supporting source
Improper verification of cryptographic signature in Copilot Studio allows an unauthorized attacker to elevate privileges over a network.msrc.microsoft.com
The record
Disclosed
2026-09-08
Vendor
Microsoft
Product
Microsoft Copilot Studio
Risk domain
Access control and permissions › Privilege escalation
System type
Generative model
Who acted
AI was the target — signature-verification flaw in the agent platform; no model decision
Attack surface
Enterprise assistant
Autonomy level
Assistant
Initial vector
Cryptographic signature forgery
Impact type
Privilege escalation
Confidence
High
Submitted by
EAI Internal
Crosswalk
- OWASP Agentic Top 10 (2026)
- ASI03 – Identity and Privilege Abuse
- MITRE ATLAS
- AML.T0055 – Unsecured Credentials
- NIST AI RMF
- GOVERN 6.1
- EU AI Act
- Article 13
- ISO/IEC
- TR 24028; 42001; 23894
- AIUC-1
- B. Security
- Scope
- tool misuse
- Mitigation
- Apply least-privilege principle; Regular policy audits.
- Taxonomy
- Enkrypt AI agent risk taxonomy · Black-Box Red Teaming of Agentic AI: A Taxonomy-Driven Framework for Automated Risk Discovery
Blast radius
Microsoft Copilot Studio (service-side; no product version listed)
Capability abused
Defense & remediation
Recorded defense
cryptographic signature verification
Guardrail kinds
Unknown
Guardrail outcome
Silent
Fix shipped
server-side (Microsoft, September 2026)
Taxonomy & references
Curator notes
CVSS 9.3 (AV:N/AC:L/PR:N/UI:N). CVE published 2026-09-03; surfaced in the September 2026 Patch Tuesday review (ZDI). MSRC: not exploited, not publicly disclosed. Copilot Studio is Microsoft's agent-building platform (cf. existing AgentFlayer / CoPhish records on the same product).
Supporting sources
Cite as
Enkrypt AI. "CVE-2026-80098: improper cryptographic signature verification in Copilot Studio allows privilege elevation". AIR, AIR-2026-0227. https://agentincident.vercel.app/i/AIR-2026-0227/ (accessed 2026-10-19).