Security readout for executives and security teams
Plain-English summary
A memory-handling flaw in several Microsoft Office editions could let an unauthenticated attacker run code on an affected computer. Successful exploitation could compromise data, alter files, or disrupt the device. The supplied CVSS score is 8.4, making this a high-severity issue.
Executive priority
Treat this as a high-priority endpoint patching issue because successful exploitation could cause full data and system impact. Expedite inventory and Microsoft update deployment, but do not characterize it as an active campaign without additional evidence.
Technical view
CVE-2026-20952 is a CWE-416 use-after-free vulnerability in Microsoft Office. The supplied CVSS v3.1 vector is AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating local access, low complexity, no privileges or user interaction, and potentially high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to the listed Microsoft 365 Apps for Enterprise, Office 2016, Office 2019, Office LTSC 2021/2024, and Office LTSC for Mac 2021/2024 versions. The bundle provides no CPEs or deployment telemetry, so organizational exposure requires inventory validation.
Exploitation context
The supplied record does not identify active exploitation, and the CVE is not listed as KEV in the bundle. Although titled remote code execution, its CVSS attack vector is local. The available evidence does not explain the delivery method, prerequisites, or whether public proof-of-concept material exists.
Researcher notes
The core weakness is use-after-free memory corruption. The vector indicates low-complexity local exploitation without privileges or user interaction, but the supplied sources do not describe the vulnerable component, trigger, exploitation chain, mitigations, or patch identifiers. Avoid inferring a document-based or network-based path from the title alone.
Mitigation direction
- Review Microsoft’s CVE advisory for the applicable security update for each listed Office edition.
- Deploy Microsoft-provided updates through the organization’s normal expedited patch process.
- Prioritize affected endpoints handling sensitive data or used by privileged personnel.
- Use existing endpoint protections and least privilege while update coverage is completed.
Validation and detection
- Inventory installed Office products, editions, platforms, and versions against the supplied affected list.
- Confirm the applicable Microsoft security update is installed on each affected endpoint.
- Verify update deployment success through endpoint-management reporting and representative device checks.
- Monitor Microsoft’s advisory for revised affected-product or remediation information.
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-416: 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-2026-20952 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
- 8.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C2.55.9microsoftVulnerability scoring details
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/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 Office 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.