{"id":"CVE-2026-45498","kind":"vulnerability","aliases":["CVE-2026-45498"],"related":[],"title":"microsoft defender antimalware platform: Microsoft Defender Denial of Service Vulnerability","description":"Microsoft Defender contains an unspecified vulnerability that allows for denial of service.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"Microsoft Defender contains an unspecified flaw that lets an attacker cause a denial of service. CISA lists it as actively exploited in the wild.","severity":"high","cvss":7.5,"epss":null,"exploited":true,"exploited_at":"2026-05-20T00:00:00+00:00","products":[{"name":"Microsoft Defender","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft defender antimalware platform","fixed":["4.18.26040.7"],"affected":"< 4.18.26040.7","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","microsoft-365","microsoft-defender","vendor","windows"],"not_affected_if":["non-microsoft-defender-environments"],"how_to_check":null,"fix":"Apply the mitigations per Microsoft's vendor instructions referenced by CISA; the sources do not name a patched version. If mitigations are unavailable, CISA says to discontinue use of the product.","status":"open","published_at":"2026-05-20T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:35:39+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"vendor","confidence":0.5,"triage":{"at":"2026-10-23T20:35:39Z","model":"claude-haiku-5-5","output":{"fix":"Apply the mitigations per Microsoft's vendor instructions referenced by CISA; the sources do not name a patched version. If mitigations are unavailable, CISA says to discontinue use of the product.","summary":"Microsoft Defender contains an unspecified flaw that lets an attacker cause a denial of service. CISA lists it as actively exploited in the wild.","category":"vendor","who_cares":["microsoft-defender","windows","microsoft-365"],"confidence":0.5,"analyst_note":"Find Microsoft's advisory for CVE-2026-45498 for affected versions, patch build, and the specific mitigation steps; check the CISA KEV entry for the due date.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["non-microsoft-defender-environments"],"severity_if_unknown":"high"},"cost_usd":0.00035,"input_tokens":2036,"output_tokens":293,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':79C '-2026':12A,15A '-365':25B '-45498':13A,16A '22':78C 'action':69C 'activ':50B 'allow':62C 'antimalwar':3A 'antimalware':21A 'appli':70C 'applic':76C 'attack':40B 'bod':77C 'caus':41B 'cisa':46B,67C 'cloud':82C 'contain':33B,57C 'cve':11A,14A 'defend':2A,6A,28B,32B,56C 'defender':18A,20A 'denial':7A,43B,64C 'discontinu':85C 'exploit':23B,51B 'flaw':36B 'follow':75C 'guidanc':80C 'instruct':74C 'let':38B 'list':47B 'microsoft':1A,5A,17A,19A,24B,27B,31B,55C 'microsoft-defend':26B 'mitig':71C,91C 'per':72C 'platform':4A,22A 'product':89C 'requir':68C 'servic':9A,45B,66C,83C 'unavail':93C 'unspecifi':35B,59C 'use':86C 'vendor':29B,73C 'vulner':10A,60C 'wild':54B 'window':30B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-05-20T00:00:00+00:00","kev":{"dateAdded":"2026-05-20","dueDate":"2026-06-03","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2026-45498","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-45498","severity":null,"published_at":"2026-05-20T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T14:39:37+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-45498","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45498","severity":null,"published_at":"2026-05-20T13:16:36+00:00","modified_at":"2026-07-23T12:10:00+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}