EUVD-2026-56755
GHSA-4p3r-qjm5-hfpj
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Local vector confirmed by description; no privileges needed, but victim must open the file (UI:R); only confidentiality is impacted.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Lifecycle Timeline
3DescriptionCVE.org
Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
AnalysisAI
Information disclosure in Microsoft Excel arises from use of uninitialized memory (CWE-908), exposing potentially sensitive heap or stack contents to an attacker when a victim opens a maliciously crafted Excel file. Affected products span the full Microsoft Office portfolio on both Windows and macOS, including Microsoft 365 Apps for Enterprise, Office LTSC 2021/2024, Office 2019, Excel 2016, and their Mac counterparts. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The victim must actively open a specially crafted Excel file - user interaction is required (UI:R per CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 5.5 (Medium) reflects a meaningful but constrained risk profile: AV:L limits the attack to the victim's machine, AC:L indicates no special conditions once delivery succeeds, PR:N means no authenticated session is needed, but UI:R gates the entire attack on the victim actively opening the file. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Excel spreadsheet containing a specially structured data element that triggers the uninitialized memory read path in Excel's parser. The file is delivered via phishing email or a compromised file share, and when the victim opens it in an affected version of Excel, memory contents from the process - potentially including recently accessed credentials, tokens, or document data - are disclosed to the attacker through a side channel embedded in the file's output behavior. … |
| Remediation | The primary fix is to apply Microsoft's released patches via the normal Office update channel. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-908 – Use of Uninitialized Resource
View allSame technique Information Disclosure
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External POC / Exploit Code
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