CVE Intelligence
High Memory corruption

CVE-2026-20952 — Microsoft Office Remote Code Execution Vulnerability

Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.

Published Jan 13, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: microsoft

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.53%
ahead of 43% of scored CVEs · Oct 14, 2026
Affects
Microsoft
365 Apps and 9 more
CVSS base
8.4
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Microsoft 365 Apps, Microsoft Microsoft 365 Apps for Enterprise, Microsoft Microsoft Office 2016…).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Microsoft 365 Apps versions not specified by the source Vulnerable NIST National Vulnerability Database
Microsoft Microsoft 365 Apps for Enterprise ≥ 16.0.1 and < https://aka.ms/OfficeSecurityReleases Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office 2016 ≥ 16.0.0 and < 16.0.5535.1000 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office 2019 ≥ 19.0.0 and < https://aka.ms/OfficeSecurityReleases Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office LTSC 2021 ≥ 16.0.1 and < https://aka.ms/OfficeSecurityReleases Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office LTSC 2024 ≥ 16.0.0 and < https://aka.ms/OfficeSecurityReleases Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office LTSC for Mac 2021 ≥ 16.0.1 and < 16.105.26011018 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Microsoft Office LTSC for Mac 2024 ≥ 16.0.0 and < 16.105.26011018 Vulnerable CVE Program (cve.org) e CISA ADP
Microsoft Office version 2016version 2019 Vulnerable NIST National Vulnerability Database
Microsoft Office Long Term Servicing Channel version 2024version 2021 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.4 CVSS 3.1 High 2.5 5.9 secure@microsoft.com via NIST National Vulnerability Database
8.4 CVSS 3.1 High — — microsoft via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: secure@microsoft.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-416 · Use After Free

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.53%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · microsoft/microsoft 365 apps for enterprise, microsoft/microsoft office 2016, microsoft/microsoft office 2019, microsoft
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 8.4
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Jan 13, 2026 · microsoft

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

Elsewhere on this site

Microsoft
every CVE for this vendor
Memory corruption
same class
CWE-416
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-108455 Microsoft Office PowerPoint Information Disclosure Vulnerability 1h
  • CVE-2026-108454 Microsoft Office PowerPoint Information Disclosure Vulnerability 1h
  • CVE-2026-108453 Microsoft Office PowerPoint Information Disclosure Vulnerability 1h
  • CVE-2026-108447 Microsoft Office Word Remote Code Execution Vulnerability 1h
  • CVE-2026-108448 Microsoft Office Outlook Remote Code Execution Vulnerability 1h
  • CVE-2026-108450 Microsoft Office Word Remote Code Execution Vulnerability 1h

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20952 is "Microsoft Office Remote Code Execution Vulnerability", rated High. It affects 365 Apps (Microsoft); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.4 describes technical severity. EPSS 0.53% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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