CVE-2026-70310 — Out-of-bounds Read in Microsoft 365 Apps

Triage

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

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, Microsoft Microsoft Office 2019…).
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.

Attack characteristics

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

Every base score collected

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

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-125 · Out-of-bounds Read

Other CVEs with this weakness →

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.

Timeline

What happened to this CVE, newest first.

• 2026
• Record published
  Oct 15, 2026
• CVSS changed · 5.5
  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 11, 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-2026-70310
  Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• High CVE-2026-97781 Microsoft Office OneNote Remote Code Execution Vulnerability 2d
• High CVE-2026-97780 Microsoft Office Excel Remote Code Execution Vulnerability 2d
• High CVE-2026-97776 Microsoft Office Excel Remote Code Execution Vulnerability 2d
• High CVE-2026-97778 Microsoft Office Excel Remote Code Execution Vulnerability 2d
• High CVE-2026-97775 Microsoft Office Excel Remote Code Execution Vulnerability 2d
• High CVE-2026-97772 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-2026-70310 is "Out-of-bounds Read in Microsoft 365 Apps", rated Medium. It affects 365 Apps (Microsoft); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 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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