CVE-2026-70105: Improper Input Validation in Microsoft Microsoft 365

6

Low

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

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

—

No EPSS score.

Affects

Microsoft

Microsoft 365 and 4 more

CVSS base

7.5

High · 2 source(s)

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.

Identify exposed assets running the affected vendor/product/version combinations (Microsoft Microsoft 365, Microsoft Office, Microsoft Office 2021…).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Microsoft	Microsoft 365	versions not specified by the source	Vulnerable	NIST National Vulnerability Database
Microsoft	Office	version 2019	Vulnerable	NIST National Vulnerability Database
Microsoft	Office 2021	versions not specified by the source	Vulnerable	NIST National Vulnerability Database
Microsoft	Office 2024	versions not specified by the source	Vulnerable	NIST National Vulnerability Database
Microsoft	Word	version 2016	Vulnerable	NIST National Vulnerability Database

Attack characteristics

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

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Every base score collected

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

Score	Version	Severity	Expl.	Impact	Scored by
7.5	CVSS 3.1	High	3.9	3.6	nvd@nist.gov via NIST National Vulnerability Database
6.5	CVSS 3.1	Medium	2.8	3.6	secure@microsoft.com via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 7.5 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-20 · Improper Input Validation

Other CVEs with this weakness →

Detection

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

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
CVSS changed · 7.5
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 20, 2026 · secure@microsoft.com

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70105
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Microsoft
every CVE for this vendor

Input validation
same class

CWE-20
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-97780 Microsoft Office Excel Remote Code Execution Vulnerability 2d
High CVE-2026-97772 Microsoft Office Excel Remote Code Execution Vulnerability 2d
Medium CVE-2026-97779 Microsoft Office Excel Information Disclosure Vulnerability 2d
High CVE-2026-97773 Microsoft Office Excel Remote Code Execution Vulnerability 2d
High CVE-2026-97775 Microsoft Office Excel Remote Code Execution Vulnerability 2d
High CVE-2026-97776 Microsoft Office Excel Remote Code Execution Vulnerability 2d

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 FIRST EPSS score.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
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-2026-70105 is "Improper Input Validation in Microsoft Microsoft 365", rated High. It affects Microsoft 365 (Microsoft); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. 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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