Threat Intelligence / CVE / CVE-2026-33825

CVE-2026-33825 — Microsoft Defender Antimalware Platform

CISA KEV
CVSS v3.1 7.8 (HIGH) · EPSS 7.0% (higher than 91.6% of all scored CVEs) · Priority 9/10 · Published 2026-04-14

As of 2026-04-14, CVE-2026-33825 is a HIGH-severity vulnerability in Microsoft Defender Antimalware Platform, CVSS v3.1 7.8, EPSS 7.0% (91.6th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-22), with a US federal remediation deadline of 2026-05-06. Threadlinqs Intelligence links 8 tracked threat campaigns to CVE-2026-33825, most recently “NightmareEclipse Coordinated Disclosure Breach Campaign: 9+ Windows Zero-Days (CVE-2026-33825, CVE-2026-41091, CVE-2026-45498, CVE-2026-45585, CVE-2026-45586) Dumped Outside Responsible Disclosure and Weaponized in Real-World Intrusions”.

Last updated: 2026-04-14

What is CVE-2026-33825?

A TOCTOU race condition in the Microsoft Defender Antimalware Platform update orchestrator allows a local low-privileged user to write an arbitrary file as SYSTEM via a symbolic-link hijack of the platform update staging directory. Proof-of-concept code was published to GitHub prior to Microsoft's advisory. No in-the-wild exploitation confirmed at release time, but the bug is trivial to weaponize and expected to appear in commodity post-exploitation toolkits within days.

The record classifies CVE-2026-33825 under weakness classes CWE-367, CWE-59. Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 151 days ago.

Severity and exploitation probability

CVSS v3.1 base score
7.8 — HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST)
7.0% probability of exploitation in the next 30 days, higher than 91.6% of all scored CVEs
CISA KEV
Listed since 2026-04-22, federal remediation deadline 2026-05-06
Threadlinqs priority
9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published
2026-04-14

Is CVE-2026-33825 being exploited?

CISA added CVE-2026-33825 to the Known Exploited Vulnerabilities catalog on 2026-04-22, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-05-06 under BOD 22-01. It currently carries a trending score of 38 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-33825

The record marks a vendor fix as available for CVE-2026-33825. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33825. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33825. Because CVE-2026-33825 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-05-06. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-33825

8 tracked threats in the Threadlinqs corpus reference CVE-2026-33825, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from threat-derived and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-33825 are available via the Threadlinqs MCP server (Purple tier). View plans →

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