Microsoft Patches Actively Exploited Zero-Day in Desktop Window Manager
On January 13, 2026, Microsoft released a critical security update as part of its Patch Tuesday cycle to address a zero-day vulnerability in the Desktop Window Manager (DWM), tracked as CVE-2026-20805. The flaw, which had been exploited in the wild, enables low-privilege local attackers to disclose sensitive user-mode memory specifically section addresses via remote ALPC ports.
The vulnerability poses a significant risk as it can be leveraged in privilege escalation attacks, particularly in post-compromise scenarios. Due to its low attack complexity and active exploitation, Microsoft urged organizations to prioritize patching, especially on legacy Windows systems.
The update mitigates the threat, but the discovery underscores the ongoing targeting of Windows components in cyberattack chains. No additional details on the attackers or affected organizations were disclosed.
Source: https://www.linkedin.com/feed/update/urn:li:activity:7417041341341134848
Microsoft Security Response Center cybersecurity rating report: https://www.rankiteo.com/company/microsoft-security-response-center
"id": "MIC1768386818",
"linkid": "microsoft-security-response-center",
"type": "Vulnerability",
"date": "1/2026",
"severity": "25",
"impact": "1",
"explanation": "Attack without any consequences"{'affected_entities': [{'industry': 'Software',
'name': 'Microsoft',
'type': 'Technology Company'}],
'attack_vector': 'Local',
'data_breach': {'sensitivity_of_data': 'High',
'type_of_data_compromised': 'Sensitive user-mode memory '
'(section addresses)'},
'date_publicly_disclosed': '2026-01-13',
'date_resolved': '2026-01-13',
'description': 'Microsoft patched a critical zero-day information disclosure '
'flaw in its Desktop Window Manager (DWM) after detecting '
'active exploitation in the wild. The vulnerability '
'(CVE-2026-20805) allows low-privilege local attackers to '
'expose sensitive user-mode memory, specifically section '
'addresses, via remote ALPC ports, aiding further privilege '
'escalation chains in real-world attacks.',
'impact': {'data_compromised': 'Sensitive user-mode memory (section '
'addresses)',
'systems_affected': 'Legacy Windows systems'},
'post_incident_analysis': {'corrective_actions': 'Patch released in January '
'2026 Patch Tuesday update',
'root_causes': 'Zero-day vulnerability in Desktop '
'Window Manager (DWM) allowing '
'sensitive memory disclosure via '
'ALPC ports'},
'recommendations': 'Legacy Windows estates should prioritize this patch '
'immediately to prevent privilege escalation attacks.',
'references': [{'source': 'LinkedIn Cybersecurity News Weekly Newsletter'}],
'response': {'containment_measures': 'Patch deployment',
'remediation_measures': 'Critical patch released in Patch '
'Tuesday update'},
'title': 'Microsoft Desktop Window Manager Zero-Day Vulnerability '
'(CVE-2026-20805)',
'type': 'Information Disclosure',
'vulnerability_exploited': 'CVE-2026-20805'}