PatchTheCVECVE-2026-55017: Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
CVE-2026-55017 is a high-severity flaw (CVSS 7.8) affecting 365 apps, office 2016, office 2019. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Why this priority
- High severity
- On your watchlist
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 7.8 (High) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | Required |
| EPSS exploit chance | 0.5% (top 60%) |
| CISA exploited list | No |
| Weakness | CWE-122 |
| Published | 2026-07-14 |
| Last modified | 2026-07-16 |
Last updated 2026-07-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-55017?
365 apps: mitigate or apply the listed mitigation; office 2016: mitigate or apply the listed mitigation; office 2019: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-55017 being exploited?
CVE-2026-55017 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-55017 affect?
CVE-2026-55017 affects 365 apps, office 2016, office 2019. Severity is high (CVSS 7.8). Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
How urgent is CVE-2026-55017?
Priority 42/100. High severity; On your watchlist
Software pages
Microsoft Office vulnerabilities
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