CVE-2026-70310: Microsoft Word Information Disclosure Vulnerability
CVE-2026-70310 is an information disclosure vulnerability in Microsoft Word, rated Important by Microsoft, with a CVSS 3.1 base score of 5.5 (Medium). An attacker can exploit it by an attacker with local access, without any privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. The EPSS model estimates a 0.43% probability of exploitation activity in the next 30 days, higher than 38% of all scored vulnerabilities. Microsoft released the fix on 11 August 2026 in the August 2026 Patch Tuesday, delivered through 1 security update (KB5002901). It affects 13 products in 1 product family (Microsoft Office).
Key facts
- CVE ID
- CVE-2026-70310
- Severity
- Medium CVSS 5.5
- Microsoft severity
- Important
- Impact
- Information Disclosure
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Less Likely
- Weakness
- CWE-125
- EPSS
- 0.43% (percentile 38%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- August 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-70310 at 5.5 (temporal 4.8) using CVSS 3.1. 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
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | None |
| Availability impact | None |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
Frequently asked questions (Microsoft)
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
What type of information could be disclosed by this vulnerability?
An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.
Affected products (13)
Microsoft Office
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft Office 2019 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office 2019 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft 365 Apps for Enterprise for 32-bit Systems | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft 365 Apps for Enterprise for 64-bit Systems | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC for Mac 2021 | Release Notes | Security Update | 16.112.26081010 | Maybe |
| Microsoft Office LTSC 2021 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2021 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2024 for 32-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC 2024 for 64-bit editions | Click to Run | Security Update | https://aka.ms/OfficeSecurityReleases | No |
| Microsoft Office LTSC for Mac 2024 | Release Notes | Security Update | 16.112.26081010 | Maybe |
| Microsoft Word 2016 (32-bit edition) | KB5002901 | Security Update | 16.0.5565.1000 | Maybe |
| Microsoft Word 2016 (64-bit edition) | KB5002901 | Security Update | 16.0.5565.1000 | Maybe |
| Microsoft Office 365 for Mac | Release Notes | Security Update | 16.112.26081010 | Maybe |
Security updates (1)
- KB5002901 (Security Update)
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 5.5 (MEDIUM)
- NVD weakness
- CWE-125
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| 365 apps (x64) | all listed versions |
| 365 apps (x86) | all listed versions |
| microsoft 365 | all listed versions |
| office 2019 (x64) | all listed versions |
| office 2019 (x86) | all listed versions |
| office 2021 (x64) | all listed versions |
| office 2021 (x86) | all listed versions |
| office 2021 | all listed versions |
| office 2024 (x64) | all listed versions |
| office 2024 (x86) | all listed versions |
| office 2024 | all listed versions |
| word 2016 (x64) | all listed versions |
| word 2016 (x86) | all listed versions |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70310 (Vendor Advisory)
Acknowledgments
- 0ccbbf129444eb66344ccafb92b00df4
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. | |
| 1.1 | Updated an acknowledgement. This is an informational change only. |