Microsoft XML Core Services Information Disclosure Vulnerability
What it is
Microsoft XML Core Services (MSXML) improperly handles objects in memory, allowing attackers to test for files on disk via a crafted web site.
VulnCheck tracked exploitation 1897 days before CISA's KEV listing. VulnCheck's broader catalog of in-the-wild exploitation evidence picked this up before it landed on CISA's formal list. Per-CVE fact about this entry; not a population claim about lead time in general.
Who's affected
Affects anyone running Microsoft XML Core Services. Microsoft products in a small practice typically sit close to credentials, email, or document workflows — treat the patch as in-scope.
What to do
Apply updates per vendor instructions.
If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Book a free 20-minute triage call.
Severity
CVSS base score: 6.5 — MEDIUM
Weakness classification: CWE-119
Microsoft fix
- KB4012216 (Monthly Rollup)
- KB4012213 (Security Only)
- KB4012215 (Monthly Rollup)
- KB4012212 (Security Only)
- KB4012217 (Monthly Rollup)
- KB4012214 (Security Only)
- KB3216916 (Security Update)
- KB4012606 (Security Update)
- KB4013198 (Security Update)
- KB4013429 (Security Update)
Microsoft Exploitability Index (assessed at update release): Exploitation More Likely
This CVE is on CISA's Known Exploited Vulnerabilities catalog. Microsoft's index reflects their release-time forecast, not current observed activity, and is not automatically revised upward when exploitation appears later.
Vendor workaround
No vendor workaround published. Patching is the only fix.
CISA due date
Federal deadline: June 14, 2022.Federal agencies must complete the required action by this date. For private SMBs the deadline is advisory — but treat it as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).
EPSS
EPSS score: 18.1% — higher than 97% of all scored CVEs.
EPSS estimates the probability of exploitation activity in the next 30 days. Every entry on this site is already confirmed exploited, so read it as relative urgency among the things you still have open, not as permission to wait.
Other exploited Microsoft XML Core Services entries
More CISA KEV entries for Microsoft XML Core Services. Same product line, same actively-exploited status.
Source
Pulled daily from the public cisagov/kev-data mirror (CC0). View the original entry on cisa.gov. CISA KEV is US-Government public-domain data; we add the SMB-vertical framing and the coping action above.