EUVD-2026-56415
GHSA-9c4p-v976-93rw
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Network-reachable Exchange service requires only a valid low-privileged account; heap overflow yields full code execution with no interaction and no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.
AnalysisAI
Remote code execution in Microsoft Exchange Server stems from a heap-based buffer overflow (CWE-122) exploitable by any network-accessible authenticated user with low privileges. Affected versions span Exchange Server 2016 CU23, 2019 CU14 and CU15, and the Subscription Edition - all major currently-supported release lines. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to hold a valid, authenticated Exchange account with at minimum low-privilege access (PR:L per CVSS vector) - anonymous or unauthenticated exploitation is not indicated. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 8.8 is substantiated by the vector AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - network-exploitable, low complexity, requiring only a low-privileged account, with no user interaction and full confidentiality, integrity, and availability 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 vendor-released security updates immediately: Exchange Server 2016 CU23 should be patched to version 15.01.2507.072 or later; Exchange Server 2019 CU14 to 15.02.1544.044 or later; Exchange Server 2019 CU15 to 15.02.1748.049 or later; and Exchange Server Subscription Edition to 15.02.2562.046 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, verify which Exchange Server versions are deployed (2016 CU23, 2019 CU14/CU15, or Subscription Edition) and confirm patch availability from Microsoft security advisories. …
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
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