CVE-2026-66806: Microsoft Office Word Information Disclosure Vulnerability
Off-by-one error in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
CSIRTS triage
- What
- An off-by-one error in Microsoft Office Word allows local information disclosure to an unauthorized attacker.
- Who is affected
- Systems with Microsoft Office Word where local attackers can trigger the vulnerability.
- Urgency
- Medium priority; local information disclosure with CVSS 5.5 poses limited risk in isolation.
- Action
- Apply the latest Microsoft Office security update addressing CVE-2026-66806.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66806
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-668060.42% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 35% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-66806 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- high[NEW] [high] Microsoft Office Products: Multiple Vulnerabilitiescert-bund
- unknownMultiple vulnerabilities in Microsoft Office (August 12, 2026)cert-fr-avis
- unknownNCSC-2026-0286 [1.00] [M/H] Vulnerabilities patched in Microsoft Officencsc-nl
- mediumCVE-2026-66806: Off-by-one error in Microsoft Office Word allows an unauthorized attacker to disclose informat…nvd
Recent advisories for Microsoft Office Word
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- mediumCVE-2026-70319: Improper input validation in Microsoft Office Word allows an unauthorized attacker to disclose…nvd · 2026-08-11
- highCVE-2026-70311: Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locall…nvd · 2026-08-11
- mediumCVE-2026-70310: Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose inform…nvd · 2026-08-11
- mediumCVE-2026-66810: Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to disclos…nvd · 2026-08-11
- mediumCVE-2026-66806: Off-by-one error in Microsoft Office Word allows an unauthorized attacker to disclose informat…nvd · 2026-08-11
- mediumCVE-2026-64917: Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose inform…nvd · 2026-08-11
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