Microsoft Security Update Guide · Copilot

Microsoft Copilot Information Disclosure Vulnerability

Microsoft · EN CVE-2026-55946 Critical No action needed CVSS 6.1

Published

What does this mean?

  • Information Disclosure. An attacker can see information that is not meant for them.
  • It can be exploited over the network (including from the internet if the service is reachable there), without an account and if a user takes part, for example by opening a link or file.
  • CVSS 6.1 out of 10: medium. Microsoft rates it Critical.
  • What should you do? Nothing: Microsoft fixed this in the cloud service. There is no update to install.

Microsoft Copilot · Information Disclosure

Improper neutralization of special elements used in a command ('command injection') in Microsoft Copilot allows an unauthorized attacker to disclose information over a network.

Copilot

What kind of flaw is this?

Key facts

Released
17 sep 2026
Impact
Information Disclosure
Max severity
Critical
Weakness
CVSS 3.1
6.1 / 5.3 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C
Publicly disclosed
No
Exploited
No
Exploitability assessment
N/A
Customer action required
No, fixed by Microsoft
Links

CVSS metrics

Base score metrics
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionRequired
ScopeChanged
ConfidentialityHigh
IntegrityNone
AvailabilityNone
Temporal score metrics
Exploit Code MaturityUnproven
Remediation LevelOfficial Fix
Report ConfidenceConfirmed

Affected products and updates

ProductUpdateBuild
Microsoft Copilot——

FAQ

Why are there no links to an update or instructions with steps that must be taken to protect from this vulnerability?
This vulnerability has already been fully mitigated by Microsoft. There is no action for users of this service to take. The purpose of this CVE is to provide further transparency. Please see Toward greater transparency: Unveiling Cloud Service CVEs for more information.

Revisions

VersionDateNote
117 sep 2026Information published.

View at Microsoft → ← All security advisories

Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.