How severe is CVE-2026-26134?

CVE-2026-26134 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-26134 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26134?

CVE-2026-26134 affects Microsoft 365 Copilot. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26134?

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.

Does CVE-2026-26134 have an EU (EUVD) identifier?

Yes. CVE-2026-26134 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10699.

When was CVE-2026-26134 published?

CVE-2026-26134 was published on 2026-03-10 and last updated on 2026-06-17.

CVE-2026-26134

CVE-2026-26134 is a high-severity vulnerability in Microsoft 365 Copilot 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-190.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10699
Weakness: CWE-190
Affected product: Microsoft 365 Copilot
Published: 2026-03-10
Last modified: 2026-06-17

Description

Integer overflow or wraparound in Microsoft Office allows an authorized attacker to elevate privileges locally.

Frequently asked questions

What is CVE-2026-26134?: Integer overflow or wraparound in Microsoft Office allows an authorized attacker to elevate privileges locally.
How severe is CVE-2026-26134?: CVE-2026-26134 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-26134 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26134?: CVE-2026-26134 affects Microsoft 365 Copilot. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26134?: 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.
Does CVE-2026-26134 have an EU (EUVD) identifier?: Yes. CVE-2026-26134 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10699.
When was CVE-2026-26134 published?: CVE-2026-26134 was published on 2026-03-10 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26134

Affected products (1)

cpe:2.3:a:microsoft:365_copilot:*:*:*:*:*:android:*:*

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