CVE-2026-63521: Microsoft Office Word Information Disclosure Vulnerability
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
CSIRTS triage
- What
- Out-of-bounds read allows unauthorized disclosure of local information.
- Who is affected
- Deployments of Microsoft Office Word are affected.
- Urgency
- Medium severity; not currently exploited but information disclosure can aid further attacks.
- Action
- Apply Microsoft security patches for CVE-2026-63521 when available.
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-2026-63521
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-2026-635210.29% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 22% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-63521 | 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-2026-63521: Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose inform…nvd