Microsoft Security Update Guide · Office / Microsoft 365 Apps

Microsoft Office Information Disclosure Vulnerability

Microsoft · EN CVE-2026-55026 Important Action required CVSS 6.2

Published

What does this mean?

  • Information Disclosure. An attacker can see information that is not meant for them.
  • It can be exploited with access to the device itself, without an account and without any user action.
  • CVSS 6.2 out of 10: medium. Microsoft rates it Important.
  • No attacks reported; Microsoft expects exploitation to be less likely.
  • What should you do? Install the security update for the version you run (or a later cumulative update):
    • Microsoft Office LTSC 2021 for 32-bit editions: KBClick to Run https://aka.ms/OfficeSecurityReleases
    • Microsoft Office LTSC 2024 for 64-bit editions: KBClick to Run https://aka.ms/OfficeSecurityReleases
    • Microsoft Office LTSC 2024 for 32-bit editions: KBClick to Run https://aka.ms/OfficeSecurityReleases
    • Microsoft SharePoint Server Subscription Edition: KB5002882 16.0.19725.20434
    • Microsoft Office 365 for Mac: KBRelease Notes 16.111.26071215
    • Microsoft Office 2016 (64-bit edition): KB5002887 16.0.5561.1000

Microsoft Office · Information Disclosure

Integer overflow or wraparound in Microsoft Office allows an unauthorized attacker to disclose information locally.

Office / Microsoft 365 Apps

How do I check if I am affected?

SharePoint Server: check and update

  1. Check your farm build in the SharePoint Management Shell:
    (Get-SPFarm).BuildVersion
    Or in Central Administration → Upgrade and Migration → Check product and patch installation status.
  2. If the build is equal to or higher than the build under "Affected products and updates" below, this vulnerability is fixed. A later cumulative update includes the fix too.
  3. Otherwise install the update on every server in the farm, then run the SharePoint Products Configuration Wizard, or:
    PSConfig.exe -cmd upgrade -inplace b2b -wait -cmd applicationcontent -install -cmd installfeatures -cmd secureresources -cmd services -install
  4. You do not need to update SharePoint Online in Microsoft 365; Microsoft does that.

Key facts

Released
14 jul 2026
Impact
Information Disclosure
Max severity
Important
Weakness
CVSS 3.1
6.2 / 5.4 (base / temporal)
Vector string
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Publicly disclosed
No
Exploited
No
Exploitability assessment
Exploitation Less Likely
Customer action required
Yes
Links

CVSS metrics

Base score metrics
Attack VectorLocal
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityNone
AvailabilityNone
Temporal score metrics
Exploit Code MaturityUnproven
Remediation LevelOfficial Fix
Report ConfidenceConfirmed

Affected products and updates

ProductUpdateBuild
Microsoft Office LTSC 2021 for 32-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 64-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024 for 32-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft SharePoint Server Subscription EditionKB5002882 · Security Update16.0.19725.20434
Microsoft Office 365 for MacKBRelease Notes · Security Update16.111.26071215
Microsoft Office 2016 (64-bit edition)KB5002887 · Security Update16.0.5561.1000
Microsoft Office 2016 (32-bit edition)KB5002887 · Security Update16.0.5561.1000
Microsoft Office LTSC for Mac 2024KBRelease Notes · Security Update16.111.26071215
Microsoft Office LTSC 2021 for 64-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC for Mac 2021KBRelease Notes · Security Update16.111.26071215
Microsoft 365 Apps for Enterprise for 64-bit SystemsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft 365 Apps for Enterprise for 32-bit SystemsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 64-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft Office 2019 for 32-bit editionsKBClick to Runhttps://aka.ms/OfficeSecurityReleases
Microsoft SharePoint Server 2019KB5002883 · Security Update16.0.10417.20175
Microsoft SharePoint Server 2019KB5002885 · Security Update16.0.10417.20175
Microsoft SharePoint Enterprise Server 2016KB5002891 · Security Update16.0.5561.1001
Microsoft SharePoint Enterprise Server 2016KB5002892 · Security Update16.0.5561.1001

FAQ

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.
There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Security Updates table for the software?
Yes. Customers should apply all updates offered for the software installed on their systems. If multiple updates apply, they can be installed in any order.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.

Revisions

VersionDateNote
114 jul 2026Information published.

View at Microsoft → ← All security advisories

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