EUVD-2026-73127
GHSA-4mgc-j5m2-g2pp
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Authenticated network exploitation with no complexity barrier; integrity-only impact from cross-object key manipulation, no confidentiality or availability consequence.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
4DescriptionCVE.org
Authorization bypass through user-controlled key in Microsoft Exchange Server allows an authorized attacker to perform tampering over a network.
AnalysisAI
Microsoft Exchange Server (2016 CU23, 2019 CU14/CU15, and Subscription Edition) exposes an authorization bypass via user-controlled key manipulation (CWE-639), allowing any authenticated network user to tamper with Exchange objects outside their authorized scope. An attacker with low-privilege access can substitute a manipulated object key in requests to affect mailbox data, calendar entries, or other resources belonging to other users, achieving high integrity impact with no confidentiality or availability consequence. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a valid, authenticated Exchange account with at minimum low-privilege access - unauthenticated attackers cannot exploit this vulnerability. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N yields a score of 6.5 - moderate overall but with a meaningful integrity threat. … 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 Microsoft's released security updates as the primary fix: Exchange Server 2016 CU23 should be upgraded to 15.01.2507.073 or later; Exchange Server 2019 CU14 to 15.02.1544.046 or later; Exchange Server 2019 CU15 to 15.02.1748.051 or later; and Exchange Server Subscription Edition to 15.02.2562.049 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
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