CVE-2026-80098 is a critical (CVSS 9.3) improper cryptographic signature verification flaw in Microsoft Copilot Studio that lets an unauthorized attacker elevate privileges over a network. Check the Microsoft Security Response Center entry to see whether any customer action is required.
What's affected
- Product: Microsoft Copilot Studio.
- Affected and fixed: the record gives no version. The MSRC page would not load for me, so I cannot say whether the fix is applied for you or needs action.
- Weakness: CWE-347, improper verification of cryptographic signature.
- CVSS 9.3 (critical), vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N. Not listed in CISA KEV.
How to check if you're exposed
Open the MSRC update guide entry for CVE-2026-80098 and read the FAQ and the remediation section. Microsoft states there whether the product is serviced for you or needs a customer step.
While you are there, review who can build, publish and connect agents in your tenant, and what those agents can reach. That review is useful whatever the entry says.
Write down what you find, with the owner, version and network exposure of each instance. After you patch, check again and record the fixed version, so the next advisory starts from a current inventory. You can also paste a dependency manifest into the free scan at gold.safeguard.sh/scan for any packaged components that sit alongside this product.
What to do now
- Read the MSRC entry for CVE-2026-80098.
- Follow any customer action the entry lists.
- Review agent owners, connections and the permissions behind them.
- Apply the principle of least privilege to the connectors your agents use.
Why it matters
Improper signature verification means a system accepts data as authentic without proper proof. The record says an unauthorized attacker could elevate privileges over a network, which fits a trust decision that was made on weak evidence.
The record offers little more, and I will not guess at the mechanism. For cloud services the useful habit is to read the vendor's entry, note whether action is needed, and keep connectors and permissions tight.
Quick check
Do I need to patch anything?
Read the MSRC entry. The record gives no version, so I cannot say.
Sources
Last reviewed: 19 October 2026.
