Exploited vulnerability · CISA KEV

Is CVE-2018-0798 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · Microsoft Office · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2018-0798, Microsoft Office Memory Corruption Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 1393 days after it was published. It affects Microsoft Office. If you run it, CISA's required action is: Apply updates per vendor instructions.

What it is

Microsoft Office contains a memory corruption vulnerability due to the way objects are handled in memory. Successful exploitation allows for remote code execution in the context of the current user. This vulnerability is known to be chained with CVE-2018-0802.

What to do

1. Check whether you run it. Look for Office in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply updates per vendor instructions.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 10 Jan 2018.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Office

• CVE-2026-124194: Microsoft Office Outlook Missing User Interaction for Potentially Unsafe Action Vulnerability (10 Nov 2026)
• CVE-2009-0238: Microsoft Office Remote Code Execution (14 Apr 2026)
• CVE-2026-21514: Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability (10 Feb 2026)
• CVE-2026-21509: Microsoft Office Security Feature Bypass Vulnerability (26 Jan 2026)
• CVE-2009-0556: Microsoft Office PowerPoint Code Injection Vulnerability (7 Jan 2026)
• CVE-2007-0671: Microsoft Office Excel Remote Code Execution Vulnerability (12 Aug 2025)

References

• nvd.nist.gov/vuln/detail/CVE-2018-0798

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · Microsoft scorecard · act-now radar.