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CVE-2026-77903

CRITICAL 9

Published 2026-09-17 · Last modified 2026-10-14

Authentication bypass by spoofing in Microsoft Dataverse allows an unauthorized attacker to elevate privileges over a network.

ELEVATED IMPACT

Severe if exploited (CVSS 9), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 31st percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

9CVSS 3.1 · CRITICAL

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors Microsoft

Products Microsoft Dataverse Dataverse

Weakness (CWE)

  • CWE-290: : Authentication Bypass by Spoofing

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C

References and research data (JSON)

Known Affected Software Configurations

VendorProductVersion range
MicrosoftDataverse*

All CVSS metrics

  • CRITICAL 9 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
  • CRITICAL 9 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
  • HIGH 8.1 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Patches & mitigations

Advisories

Sources: NVD · CVE.org · EPSS