Microsoft has disclosed a critical command injection flaw (CVSS 9.9) in Microsoft 365 Copilot that lets a low-privileged, authenticated attacker escalate privileges over a network with no user interaction.
What Is It
CVE-2026-85885 is an improper neutralization of special elements used in a command, a command injection issue (CWE-77), in Microsoft 365 Copilot. Per Microsoft's advisory, the flaw "allows an authorized attacker to elevate privileges over a network." The CVE was published on 2026-09-17 with a vulnerability status of "Received," meaning NVD analysis is still pending.
Why It Matters
Microsoft assigns the issue a CVSS 3.1 base score of 9.9 (Critical) with the vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. That combination is about as bad as it gets short of pre-auth access:
- Network attack vector with low attack complexity: no local access, no special conditions.
- Low privileges required and no user interaction: PR:L indicates the attacker needs some level of authorized access, but the metric alone does not specify which accounts or roles qualify. Absent further detail from Microsoft, it is reasonable to assume a relatively common privilege tier rather than a narrowly scoped administrative one, though that reading should be treated as provisional until the advisory or NVD analysis clarifies it.
- Scope: Changed: impact extends beyond the vulnerable component's security boundary, which is what pushes the score to 9.9.
- High confidentiality, integrity, and availability impact across the board.
What's Vulnerable
Microsoft lists Microsoft 365 Copilot as affected, with the version marked simply as -. The CVE is tagged exclusively-hosted-service, meaning the vulnerable component runs as a Microsoft-hosted cloud service rather than software customers install and version locally. No CPE entries are currently published in the NVD record.
Patch Status
CVE-2026-85885 does not appear in CISA's Known Exploited Vulnerabilities (KEV) Catalog, so active exploitation is not confirmed and no KEV remediation deadline applies. Because the CVE is tagged as an exclusively hosted service, remediation is handled on Microsoft's side rather than through customer-applied patches. The available record does not specify a fix version, mitigation, or workaround; consult the MSRC update guide entry below for current remediation status.
Sources
- Microsoft Security Response Center (MSRC), CVE-2026-85885: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85885
- NVD, CVE-2026-85885: https://nvd.nist.gov/vuln/detail/CVE-2026-85885
- CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog