Cyber Resilience

CVE-2026-24307

Microsoft 365 Copilot

Published
22 January 2026
Modified
12 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
EPSS Score 0.0081 54th percentile
Risk Priority 67 floored blend · peak EPSS

Summary

CVE-2026-24307 is a critical-severity Improper Validation of Specified Type of Input (CWE-1287) vulnerability in Microsoft 365 Copilot. Its CVSS base score is 9.3 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 46% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as Enterprise AI Assistants; in the Privacy and Disclosure risk domain.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-24307 is an improper validation of specified type of input vulnerability, classified under CWE-1287, affecting Microsoft 365 Copilot. Published on 2026-01-22, it carries a CVSS v3.1 base score of 9.3 (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N), marking it as critical due to its network accessibility, low complexity, lack of privilege requirements, and potential for high impacts on confidentiality and integrity across a changed scope.

An unauthorized attacker can exploit this vulnerability remotely over the network by tricking a user into interacting with malicious input, such as through a crafted prompt or file. Successful exploitation enables the attacker to disclose sensitive information and potentially manipulate data integrity, though it does not impact availability.

Microsoft's Security Response Center update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-24307 details the vulnerability, including recommended mitigations and available patches.

EU & UK References

Vulnerability Data

Improper validation of specified type of input in M365 Copilot allows an unauthorized attacker to disclose information over a network.

CWE(s)
CWE-1287

AI Security AnalysisAI

AI Category
Enterprise AI Assistants
Risk Domain
Privacy and Disclosure
OWASP Top 10 for LLMs 2025
None mapped
Classification Reason
Matched keywords: m365 copilot

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-23391Same product: Microsoft 365 Copilot
CVE-2025-59278Same vendor: Microsoft
CVE-2025-58729Same vendor: Microsoft
CVE-2026-25179Same vendor: Microsoft
CVE-2025-59259Same vendor: Microsoft
CVE-2025-55701Same vendor: Microsoft
CVE-2025-59257Same vendor: Microsoft
CVE-2026-26115Same vendor: Microsoft
CVE-2025-59277Same vendor: Microsoft
CVE-2023-36565Same product: Microsoft 365 Copilot

Affected Assets

microsoft
365 copilot
all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.1
  • V1.4.2
  • V2.1.1
  • V2.2.2

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

SI-10 directly requires validation of information inputs, which structurally prevents type-validation failures from being introduced or exploitable.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper input type validation during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect type-validation flaws but does not prevent them during development.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and type checking to prevent improper type handling.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly include validation of input data types and formats.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles promote defensive input handling and type enforcement at system boundaries.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly require proper type validation of all external inputs.

References