# CVE-2026-42824 — Microsoft 365 Copilot

> As of 2026-06-19, CVE-2026-42824 is a MEDIUM-severity vulnerability in Microsoft 365 Copilot, CVSS v3.1 6.5, EPSS 0.5% (38.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-42824, most recently “SearchLeak: Microsoft 365 Copilot Enterprise One-Click Data Exfiltration (CVE-2026-42824)”.

**Last updated:** 2026-06-19

## What is CVE-2026-42824?

Missing authentication for critical function in M365 Copilot allows an unauthorized attacker to disclose information over a network.

The record classifies CVE-2026-42824 under weakness class [CWE-77](https://intel.threadlinqs.com/cwe/CWE-77). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 123 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 6.5 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C`)
- **EPSS (FIRST):** 0.5% probability of exploitation in the next 30 days, higher than 38.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-04, last modified 2026-06-19

## Is CVE-2026-42824 being exploited?

No public exploitation evidence for CVE-2026-42824 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-06-19. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): 365 Copilot

## How to fix CVE-2026-42824

Vendor advisory: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42824](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42824). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-42824

1 tracked threat in the Threadlinqs corpus references CVE-2026-42824, either in the campaign’s CVE list or as an indicator on the campaign record.

- [SearchLeak: Microsoft 365 Copilot Enterprise One-Click Data Exfiltration (CVE-2026-42824)](https://intel.threadlinqs.com/threat/TL-2026-0806) — CRITICAL · 2026-06-15

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-06-22. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42824)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-42824
Full detection coverage and IOCs for threats exploiting CVE-2026-42824 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp