HighVulnerabilityLLM-specific

CVE-2026-26164: M365 Copilot injection flaw allows unauthorized information disclosure

Source: NVD(opens in a new tab)
Identifier: CVE-2026-26164
Published: May 7, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.8%

Summary

CVE-2026-26164 is an improper neutralization of special elements in output used by a downstream component ('injection'), classified as CWE-74, in M365 Copilot. The source states that an unauthorized attacker can disclose information over a network. NVD has not yet provided an assessment, and the record was published and last modified on 05/07/2026.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Details

Scores and exploitation

CVSS score: 7.5(high)
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector: network
Attack complexity: low
Privileges required: none
User interaction: none
EPSS: 0.8%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 10, 2026.
Disclosure date: May 7, 2026

Weaknesses and techniques

Weakness (CWE): CWE-74
AI threat technique (MITRE ATLAS): AML.T0051

Affected

Vendors: Microsoft

Classification

Attack type: Prompt injection
Attack sophistication: Moderate
AI component targeted: Plugin
Impact: Confidentiality
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-26164

First tracked: May 7, 2026 at 08:08 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 85% (self-assessed)

Topics

Coding assistants

Summary

Mitigation

Topics

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