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CVE-2026-55054

MEDIUM 6.5

Published 2026-07-14 · Last modified 2026-07-21

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.6%chance of exploitation in 30 days · 46th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

6.5CVSS 3.1 · MEDIUM

  • ConfidentialityHigh
  • IntegrityNone
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: A user must take an action (click / open a file)
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-55054/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-55054/poc.json

Affected

Vendors Microsoft Apple

Products Microsoft 365 Apps For Enterprise Microsoft Excel 2016 Microsoft Office 2019 Microsoft Office 365 For Mac Microsoft Office Ltsc 2021 Microsoft Office Ltsc 2024 Microsoft Office Ltsc For Mac 2021 Microsoft Office Ltsc For Mac 2024 Office Online Server 365 Apps Excel Office

Weakness (CWE)

  • CWE-125: : Out-of-bounds Read

CVSS vector

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

Known Affected Software Configurations

VendorProductVersion range
Microsoft365 Apps*
Microsoft365 Apps*
MicrosoftExcel2016
MicrosoftExcel2016
MicrosoftOffice2019
MicrosoftOffice2019
MicrosoftOffice 2021< 16.111.26071215
MicrosoftOffice 2021*
MicrosoftOffice 2021*
MicrosoftOffice 2024< 16.111.26071215
MicrosoftOffice 2024*
MicrosoftOffice 2024*
MicrosoftOffice Online Server< 16.0.10417.20175
MicrosoftOffice 365< 16.111.26071215

All CVSS metrics

  • MEDIUM 6.5 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
  • MEDIUM 6.5 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

References

Patches & mitigations

Sources: NVD · CVE.org · EPSS