CVE-2026-66806medium5.5

Microsoft Office Word Information Disclosure Vulnerability

Impact

Microsoft Office Word has an off-by-one error, allowing local information disclosure. Affected versions include Microsoft 365 Apps for Enterprise 16.0.1, Microsoft Office 2019 19.0.0, Microsoft Office LTSC 2021 16.0.1, and Microsoft Office LTSC 2024 16.0.0. An attacker with local access can exploit this vulnerability.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Microsoft · microsoft

Microsoft 365 Apps for Enterprise

1 range

microsoft version evidence

Platforms: 32-bit Systems, x64-based Systems

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

16.0.1 → before https://aka.ms/OfficeSecurityReleases

custom versions

Other versions: unknown

Microsoft · microsoft

Microsoft Office 2019

1 range

microsoft version evidence

Platforms: 32-bit Systems, x64-based Systems

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

19.0.0 → before https://aka.ms/OfficeSecurityReleases

custom versions

Other versions: unknown

Microsoft · microsoft

Microsoft Office LTSC 2021

1 range

microsoft version evidence

Platforms: 32-bit Systems, x64-based Systems

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

16.0.1 → before https://aka.ms/OfficeSecurityReleases

custom versions

Other versions: unknown

Microsoft · microsoft

Microsoft Office LTSC 2024

1 range

microsoft version evidence

Platforms: 32-bit Systems, x64-based Systems

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

16.0.0 → before https://aka.ms/OfficeSecurityReleases

custom versions

Other versions: unknown

Microsoft · microsoft

Microsoft Word 2016

1 range

microsoft version evidence

Platforms: 32-bit Systems, x64-based Systems

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

16.0.1 → before 16.0.5565.1000

custom versions

Other versions: unknown

Original source description

Off-by-one error in Microsoft Office Word allows an unauthorized attacker to disclose information locally.

Inside the record

Evidence available

Package identity · not supplied

Version evidence

Remediation guidance · not supplied

Weakness classification

Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-66806

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-193 ↗

CWE-193: Off-by-one Error

microsoft

CWE-125 ↗

CWE-125: Out-of-bounds Read

microsoft

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

microsoft · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:a:microsoft:office_2019:*:*:*:*:*:*:*:*

From (inclusive): 19.0.0

After:

Through (inclusive):

Before: https://aka.ms/OfficeSecurityReleases

Vulnerable product

cpe:2.3:a:microsoft:365_apps:*:*:*:*:enterprise:*:*:*

From (inclusive): 16.0.1

After:

Through (inclusive):

Before: https://aka.ms/OfficeSecurityReleases

Vulnerable product

cpe:2.3:a:microsoft:office_2021:*:*:*:*:long_term_servicing_channel:*:*:*

From (inclusive): 16.0.1

After:

Through (inclusive):

Before: https://aka.ms/OfficeSecurityReleases

Vulnerable product

cpe:2.3:a:microsoft:office_2024:*:*:*:*:long_term_servicing_channel:*:*:*

From (inclusive): 16.0.0

After:

Through (inclusive):

Before: https://aka.ms/OfficeSecurityReleases

Vulnerable product

cpe:2.3:a:microsoft:word_2016:*:*:*:*:*:*:*:*

From (inclusive): 16.0.1

After:

Through (inclusive):

Before: 16.0.5565.1000

Original applicability statements

[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:microsoft:office_2019:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "19.0.0",
            "versionEndExcluding": "https://aka.ms/OfficeSecurityReleases"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:microsoft:365_apps:*:*:*:*:enterprise:*:*:*",
            "versionStartIncluding": "16.0.1",
            "versionEndExcluding": "https://aka.ms/OfficeSecurityReleases"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:microsoft:office_2021:*:*:*:*:long_term_servicing_channel:*:*:*",
            "versionStartIncluding": "16.0.1",
            "versionEndExcluding": "https://aka.ms/OfficeSecurityReleases"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:microsoft:office_2024:*:*:*:*:long_term_servicing_channel:*:*:*",
            "versionStartIncluding": "16.0.0",
            "versionEndExcluding": "https://aka.ms/OfficeSecurityReleases"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:microsoft:word_2016:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "16.0.1",
            "versionEndExcluding": "16.0.5565.1000"
          }
        ]
      }
    ]
  }
]

Contributing organizations · 2

microsoft

Assigning organization

2026-10-30

CISA-ADP

Additional data publisher

2026-08-11

What changed

Follow changes

No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.

References

1 sources

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66806

vendor-advisorymicrosoft

Priority and evidence

Not in CISA KEVNo package fix recorded

KEV coverage does not rule out exploitation.

KEV checked 31/10/2026, 10:20:31 UTC

microsoft · CVSS:3.1 · 5.5

Assessment vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Reading the signals

Severity · CVSS: Technical impact and attack conditions. The headline is the highest imported catalog score; sources may disagree.
Observed exploitation · KEV: An absent or unavailable KEV listing does not establish that exploitation has not occurred.
Predicted exploitation · EPSS: 0.43% estimated probability in the next 30 days. 2026-10-28 · FIRST EPSS.

CISA-ADP · SSVC

CISA Coordinator · 2026-08-11

Exploitation: none
Automatable: no
Technical Impact: partial

SSVC describes the publisher’s decision context. Your organization’s exposure and priorities may differ.

Record details

Published: 11/08/2026, 17:07:02 UTC
Modified: 30/10/2026, 17:22:48 UTC
Last imported by cve.new: 30/10/2026, 19:02:17 UTC
Aliases: None recorded

Source evidence

Request a correction or dispute

Start with the assigning organization for this record. Include the CVE ID, the disputed information, and supporting evidence. A dispute does not itself reject a record.

Find the responsible CNA →Official dispute and escalation process ↗

CVE CVE-2026-66806