{"id":"CVE-2026-56155","kind":"vulnerability","aliases":["CVE-2026-56155"],"related":[],"title":"Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized…","description":"Microsoft Active Directory Federation Services contains an insufficient granularity of access control vulnerability that allows an authorized attacker to elevate privileges locally.\n\nCISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","summary":"Microsoft Active Directory Federation Services has an access control flaw that lets an authorized local user elevate their privileges. CISA lists it as actively exploited in the wild.","severity":"high","cvss":7.8,"epss":null,"exploited":true,"exploited_at":"2026-07-14T00:00:00+00:00","products":[{"name":"Microsoft Active Directory Federation Services","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft windows 10 1607","fixed":["10.0.14393.9339"],"affected":"< 10.0.14393.9339","ecosystem":"vendor"},{"name":"microsoft windows 10 1809","fixed":["10.0.17763.9020"],"affected":"< 10.0.17763.9020","ecosystem":"vendor"},{"name":"microsoft windows server 2012","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"microsoft windows server 2012","fixed":[],"affected":"= r2","ecosystem":"vendor"},{"name":"microsoft windows server 2016","fixed":["10.0.14393.9339"],"affected":"< 10.0.14393.9339","ecosystem":"vendor"},{"name":"microsoft windows server 2019","fixed":["10.0.17763.9020"],"affected":"< 10.0.17763.9020","ecosystem":"vendor"},{"name":"microsoft windows server 2022","fixed":["10.0.20348.5386"],"affected":"< 10.0.20348.5386","ecosystem":"vendor"},{"name":"microsoft windows server 2025","fixed":["10.0.26100.33158"],"affected":"< 10.0.26100.33158","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["active-directory-federation-services","exploited","microsoft","vendor","windows-server"],"not_affected_if":["no-adfs-deployment"],"how_to_check":null,"fix":"Apply the mitigations and patches from Microsoft's advisory for CVE-2026-56155, following CISA BOD 26-04 guidance; discontinue use of the product if mitigations are unavailable.","status":"open","published_at":"2026-07-14T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:33:41+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-10-23T20:33:41Z","model":"claude-haiku-5-5","output":{"fix":"Apply the mitigations and patches from Microsoft's advisory for CVE-2026-56155, following CISA BOD 26-04 guidance; discontinue use of the product if mitigations are unavailable.","summary":"Microsoft Active Directory Federation Services has an access control flaw that lets an authorized local user elevate their privileges. CISA lists it as actively exploited in the wild.","category":"vendor","who_cares":["active-directory-federation-services","windows-server","microsoft"],"confidence":0.6,"analyst_note":"Find the Microsoft Security Response Center advisory for CVE-2026-56155 to get affected builds, patched versions, and detection guidance; the sources give none of these.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-adfs-deployment"],"severity_if_unknown":"high"},"cost_usd":0.00037,"input_tokens":2219,"output_tokens":297,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-04':137C,163C,194C '-2026':17A,20A '-56155':18A,21A '10':29A,33A '1607':30A '1809':34A '2012':38A,42A '2016':46A '2019':50A '2022':54A '2025':58A '26':136C,162C,193C 'access':4A,77B,108C 'accord':126C 'action':122C 'activ':7A,60B,71B,93B,99C 'active':23A 'active-directory-federation-servic':59B 'ad':11A 'adher':190C 'allow':13A,112C 'appli':123C 'applic':160C 'asset':184C 'attack':115C 'author':15A,83B,114C 'base':141C 'bod':135C,161C,192C 'cisa':89B,120C,133C,150C 'cloud':166C 'complianc':131C 'contain':103C 'control':5A,78B,109C 'cve':16A,19A 'directori':8A,61B,72B,100C 'directory':24A 'discontinu':169C 'elev':86B,117C 'ensur':130C,189C 'evalu':182C 'exploit':64B,94B 'exposur':187C 'feder':9A,62B,73B,101C 'federation':25A 'flaw':79B 'follow':159C 'forens':152C 'fs':12A 'granular':2A,106C 'guidanc':148C,164C 'guidelin':196C 'instruct':129C 'insuffici':1A,105C 'internet':186C 'let':81B 'list':90B 'local':84B,119C 'microsoft':22A,27A,31A,35A,39A,43A,47A,51A,55A,65B,70B,98C 'mitig':124C,175C 'note':147C,158C 'patch':195C 'priorit':138C 'privileg':88B,118C 'product':173C 'requir':121C,154C 'respons':180C 'risk':143C 'secur':139C 'see':144C,155C 'server':37A,41A,45A,49A,53A,57A,69B 'servic':10A,63B,74B,102C,167C 'services':26A 'stakehold':178C 'triag':153C 'unavail':177C 'updat':140C 'url':145C,156C 'use':170C 'user':85B 'vendor':66B,128C 'vulner':110C 'wild':97B 'window':68B 'windows':28A,32A,36A,40A,44A,48A,52A,56A 'windows-serv':67B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-07-14T00:00:00+00:00","kev":{"dateAdded":"2026-07-14","dueDate":"2026-07-28","requiredAction":"Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"secure@microsoft.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2026-56155","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-56155","severity":null,"published_at":"2026-07-14T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T12:39:21+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-56155","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56155","severity":null,"published_at":"2026-07-14T17:17:09+00:00","modified_at":"2026-07-15T14:18:24+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"}