---
id: "CVE-2012-1889"
kind: "vulnerability"
aliases: ["CVE-2012-1889"]
title: "Microsoft XML Core Services 3.0, 4.0, 5.0, and 6.0 accesses uninitialized memory locations, which allows remote\u2026"
severity: "critical"
cvss: 9.3
epss: 0.83516
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Microsoft XML Core Services", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft xml core services", "fixed": [], "affected": "= 3.0", "ecosystem": "vendor"}, {"name": "microsoft xml core services", "fixed": [], "affected": "= 4.0", "ecosystem": "vendor"}, {"name": "microsoft xml core services", "fixed": [], "affected": "= 6.0", "ecosystem": "vendor"}, {"name": "microsoft xml core services", "fixed": [], "affected": "= 5.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "infrastructure", "internet-explorer", "msxml", "windows"]
not_affected_if: ["unknown"]
published_at: "2012-06-13T04:46:46+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T22:29:04+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2012-1889", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2012-1889", "first_seen_at": "2026-10-23T19:13:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2012-1889", "first_seen_at": "2026-10-23T22:29:04+00:00"}]
---

# Microsoft XML Core Services 3.0, 4.0, 5.0, and 6.0 accesses uninitialized memory locations, which allows remote…

Microsoft XML Core Services (MSXML) has a memory corruption bug that an attacker can trigger to run code on the affected Windows machine. CISA lists it as actively exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft XML Core Services affected ? fixed ?
- vendor:microsoft xml core services affected = 3.0 fixed ?
- vendor:microsoft xml core services affected = 4.0 fixed ?
- vendor:microsoft xml core services affected = 6.0 fixed ?
- vendor:microsoft xml core services affected = 5.0 fixed ?

## Fix

Apply the Microsoft updates for MSXML per vendor instructions, as CISA requires; the specific patch KB and fixed version are not in the sources.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2012-1889
- 2026-10-23T19:13:45+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2012-1889
- 2026-10-23T22:29:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2012-1889

## From the sources

Microsoft XML Core Services 3.0, 4.0, 5.0, and 6.0 accesses uninitialized memory locations, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_