EUVD-2026-56457
GHSA-xm9g-6f9f-23pj
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Local file-open trigger (AV:L), no system privileges needed by attacker (PR:N), user must open file (UI:R), impact is memory disclosure only with no write or crash.
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
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
AnalysisAI
Out-of-bounds read (CWE-125) in Microsoft Excel triggers information disclosure when a victim opens a specially crafted spreadsheet file, exposing potentially sensitive memory contents to a local attacker. The flaw spans multiple Office product lines - Excel 2016, Office 2019, Office LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and corresponding Mac variants - with high confidentiality impact but no integrity or availability consequences. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the victim opens a specially crafted Excel file using an affected version of Microsoft Excel or one of the bundled Office products - this is the sole documented prerequisite. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 5.5 medium score reflects the constrained impact profile: high confidentiality impact (C:H) but zero integrity or availability consequence, a local-only attack vector (AV:L), and mandatory user interaction (UI:R). … 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 file structure designed to trigger the out-of-bounds read in the Office parser and delivers it to a target via phishing email or a shared network location. When the victim opens the file in an unpatched version of Excel, the parser reads beyond the allocated buffer, potentially exposing adjacent memory contents - such as cached credentials, document data, or heap artefacts - which could be encoded back to the attacker via file output or a secondary exfiltration channel. … |
| Remediation | The primary fix is to apply the Microsoft-released security update for each affected product. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Information Disclosure
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External POC / Exploit Code
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