Microsoft 365 Apps for Enterprise: Improper Neutralization of Special Elements used in a Command
CVE-2026-65656 is a high-severity improper neutralization of special elements used in a command vulnerability in Microsoft 365 Apps for Enterprise from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version https://aka.ms/OfficeSecurityReleases as the first without the flaw, so updating Microsoft 365 Apps for Enterprise to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.46% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Microsoft 365 Apps for Enterprise to https://aka.ms/OfficeSecurityReleases or a later version.
- Update Microsoft Office 2019 to https://aka.ms/OfficeSecurityReleases or a later version.
- Update Microsoft Office LTSC 2021 to https://aka.ms/OfficeSecurityReleases or a later version.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Microsoft 365 Apps for Enterprise | 16.0.1 up to, but not including, https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft | Microsoft Office 2019 | 19.0.0 up to, but not including, https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft | Microsoft Office LTSC 2021 | 16.0.1 up to, but not including, https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft | Microsoft Office LTSC 2024 | 16.0.0 up to, but not including, https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft | 365 Apps | Not specified in the record | Not stated |
| Microsoft | Office 2019 | Not specified in the record | Not stated |
| Microsoft | Office 2021 | Not specified in the record | Not stated |
| Microsoft | Office 2024 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).
Official description
Improper neutralization of special elements used in a command ('command injection') in Microsoft Office allows an unauthorized attacker to execute code locally.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in a Command
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- If possible, ensure that all external commands called from the program are statically created.
- Run time: Run time policy enforcement may be used in an allowlist fashion to prevent use of any non-sanctioned commands.
More Improper Neutralization of Special Elements used in a Command vulnerabilities (CWE-77)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Microsoft 365 Apps for Enterprise
- 8.8 High severity
- 6.5 Medium severity
Recent Improper Neutralization of Special Elements used in a Command vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 7.2 High severity
- 8.8 High severity
- 7.3 High severity
- 9.3 Critical severity
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