How severe is CVE-2026-55136?

CVE-2026-55136 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-55136 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-55136?

CVE-2026-55136 primarily affects Microsoft 365 Apps. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-55136?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-55136 published?

CVE-2026-55136 was published on 2026-07-14 and last updated on 2026-07-15.

CVE-2026-55136

CVE-2026-55136 is a high-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-822.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-822
Affected product: Microsoft 365 Apps
Published: 2026-07-14
Last modified: 2026-07-15

Description

Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Frequently asked questions

What is CVE-2026-55136?: Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
How severe is CVE-2026-55136?: CVE-2026-55136 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-55136 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-55136?: CVE-2026-55136 primarily affects Microsoft 365 Apps. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-55136?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-55136 published?: CVE-2026-55136 was published on 2026-07-14 and last updated on 2026-07-15.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55136

Affected products (14)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:microsoft_365:-:*:*:*:*:macos:*:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x86:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:macos:-:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:macos:-:*
cpe:2.3:a:microsoft:office_online_server:*:*:*:*:*:*:*:*

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