How severe is CVE-2026-42827?

CVE-2026-42827 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-42827 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42827?

CVE-2026-42827 affects Microsoft 365 Copilot. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42827?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42827 have an EU (EUVD) identifier?

Yes. CVE-2026-42827 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31513.

When was CVE-2026-42827 published?

CVE-2026-42827 was published on 2026-05-22 and last updated on 2026-07-23.

CVE-2026-42827

CVE-2026-42827 is a medium-severity vulnerability in Microsoft 365 Copilot with a CVSS 3.x base score of 6.5. 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-77.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31513
Weakness: CWE-77
Affected product: Microsoft 365 Copilot
Published: 2026-05-22
Last modified: 2026-07-23

Description

Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Frequently asked questions

What is CVE-2026-42827?: Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.
How severe is CVE-2026-42827?: CVE-2026-42827 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-42827 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42827?: CVE-2026-42827 affects Microsoft 365 Copilot. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42827?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42827 have an EU (EUVD) identifier?: Yes. CVE-2026-42827 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31513.
When was CVE-2026-42827 published?: CVE-2026-42827 was published on 2026-05-22 and last updated on 2026-07-23.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42827

Affected products (1)

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

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