Cyber Posture

CVE-2026-26164

High

Published: 07 May 2026

Published
07 May 2026
Modified
08 May 2026
KEV Added
Patch
CVSS Score 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS Score 0.0008 22.6th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-26164 is a high-severity Injection (CWE-74) vulnerability in Microsoft 365 Copilot Chat. Its CVSS base score is 7.5 (High).

Operationally, ranked at the 22.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as Enterprise AI Assistants.

Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-74

Developer assessments and testing (including injection-focused techniques) identify improper neutralization of special elements, and the verifiable flaw remediation corrects them pre-deployment.

addresses: CWE-74

Identifies indicators of injection attacks (command, SQL, LDAP, etc.) via anomaly and attack monitoring.

NVD Description

Improper neutralization of special elements in output used by a downstream component ('injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)

Affected Products

microsoft
365 copilot chat
all versions

AI Security AnalysisAI

AI Category
Enterprise AI Assistants
Risk Domain
N/A
OWASP Top 10 for LLMs 2025
None mapped
Classification Reason
Matched keywords: copilot

CVEs Like This One

CVE-2025-53787Same product: Microsoft 365 Copilot Chat
CVE-2026-26129Same product: Microsoft 365 Copilot Chat
CVE-2026-26137Same product: Microsoft 365 Copilot Chat
CVE-2025-59272Same product: Microsoft 365 Copilot Chat
CVE-2025-59286Same product: Microsoft 365 Copilot Chat
CVE-2026-21521Same vendor: Microsoft
CVE-2026-21523Same vendor: Microsoft
CVE-2026-26136Same vendor: Microsoft
CVE-2026-26133Same vendor: Microsoft
CVE-2026-24307Same vendor: Microsoft

References