Security readout for executives and security teams
Plain-English summary
A flaw in affected Microsoft Excel and Office releases can let an attacker run code after a user interacts with malicious content. Successful exploitation could expose data, alter systems, or disrupt operations. The supplied CVSS score is 7.8, rated high.
Executive priority
Treat as a high-priority patching issue because successful exploitation can cause complete confidentiality, integrity, and availability impact. Accelerate remediation for users frequently receiving external Office content, while recognizing that the supplied evidence does not show active exploitation.
Technical view
CVE-2026-20956 is a CWE-822 untrusted pointer dereference in Microsoft Office Excel. The CVSS vector indicates local attack access, low complexity, no privileges, required user interaction, unchanged scope, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure applies to organizations using the listed Microsoft 365 Apps for Enterprise or Office LTSC 2021/2024 releases, including specified Mac editions. The bundle does not provide affected build ranges, deployment prevalence, or content-delivery details.
Exploitation context
The supplied data marks this CVE as absent from KEV and does not report active exploitation. User interaction is required. Absence from KEV does not establish that exploitation is impossible or has never occurred.
Researcher notes
The record identifies an untrusted pointer dereference but provides no root-cause detail, vulnerable code path, attack-content format, or proof-of-concept information. Confirm affected and fixed builds through MSRC. Do not infer exploitation from the recent record update alone.
Mitigation direction
- Review Microsoft's CVE advisory for applicable security updates and affected build details.
- Apply the vendor-provided update to affected Office installations using normal change controls.
- Prioritize systems whose users regularly handle untrusted Excel content.
- Use existing controls to restrict or isolate untrusted Office content until patching completes.
Validation and detection
- Inventory installed Microsoft 365 Apps and Office LTSC editions across Windows and Mac systems.
- Compare installed builds with Microsoft's current affected and remediated build information.
- Confirm security updates installed successfully through endpoint-management and Office update reporting.
- Re-scan endpoints and investigate update failures or unsupported installations.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-822: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-20956 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.85.9microsoftVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft Excel Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Untrusted Pointer Dereference
Untrusted Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.