EUVD-2026-54316
GHSA-p2wf-cwq4-f5gj
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Network-reachable JWT forgery requires no credentials or interaction; integrity-only impact reflects impersonation with no data exposure or disruption.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Improper verification of cryptographic signature in Microsoft Teams allows an unauthorized attacker to perform spoofing over a network.
AnalysisAI
Cryptographic signature spoofing in Microsoft Teams exposes enterprise collaboration environments to unauthenticated identity impersonation over the network. The flaw, tagged as a JWT attack enabling authentication bypass, allows a remote attacker with no prior credentials to forge or tamper with token-based identity claims that Teams fails to properly verify. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Based on the CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N, no special conditions are required - this is remote unauthenticated exploitation over the network against Microsoft Teams without victim interaction. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.5 (High) score is driven by an exceptionally permissive vector: AV:N (network-reachable), AC:L (no special conditions), PR:N (no authentication), UI:N (no victim interaction), resulting in I:H (high integrity impact). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released patch by following the guidance in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62918 - an exact patched version number is not independently confirmed from the available data and should be verified there. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: enable enhanced logging on all Teams identity and authentication operations; audit sign-in logs and token validation events for anomalous patterns indicative of identity spoofing. …
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External POC / Exploit Code
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