CVE-2026-50517
CVE-2026-50517 is a critical-severity vulnerability in Microsoft 365 Copilot with a CVSS 3.x base score of 9.9. 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-502.
Key facts
- Severity: Critical (CVSS 3.x base score 9.9)
- EPSS exploit prediction: 2% (76th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-502
- Affected product: Microsoft 365 Copilot
- Published:
- Last modified:
Description
Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.
Frequently asked questions
- What is CVE-2026-50517?
- Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.
- How severe is CVE-2026-50517?
- CVE-2026-50517 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-50517 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (76th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-50517?
- CVE-2026-50517 affects Microsoft 365 Copilot. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-50517?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-50517 published?
- CVE-2026-50517 was published on 2026-07-24 and last updated on 2026-07-29.
References
Affected products (1)
- cpe:2.3:a:microsoft:365_copilot:-:*:*:*:*:*:*:*
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