What is CVE-2026-56155?
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.
The record classifies CVE-2026-56155 under weakness class CWE-1220. 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. 12 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 106 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/E:F/RL:O/RC:C - CISA KEV
- Listed since 2026-07-14, federal remediation deadline 2026-07-28
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2026-07-14
Is CVE-2026-56155 being exploited?
CISA added CVE-2026-56155 to the Known Exploited Vulnerabilities catalog on 2026-07-14, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-07-28 under BOD 22-01. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.
Affected products and versions
- Microsoft: Windows 10 Version 1607, Windows 10 Version 1809, Windows Server 2012, Windows Server 2012 (Server Core installation), Windows Server 2012 R2, Windows Server 2012 R2 (Server Core installation), Windows Server 2016, Windows Server 2016 (Server Core installation), Windows Server 2019, Windows Server 2019 (Server Core installation), Windows Server 2022, Windows Server 2025
How to fix CVE-2026-56155
Because CVE-2026-56155 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-07-28. No vendor patch reference has been recorded for CVE-2026-56155 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-56155
17 tracked threats in the Threadlinqs corpus reference CVE-2026-56155, either in the campaign’s CVE list or as an indicator on the campaign record.
- Microsoft July 2026 Patch Tuesday: Two Actively Exploited Zero-Days (CVE-2026-56155 AD FS, CVE-2026-56164 SharePoint) Among Record 570+ Fixes — HIGH · 2026-07-17
- July 2026 Patch Tuesday: Actively Exploited SharePoint RCE (CVE-2026-58644) and AD FS/SharePoint Zero-Days — CRITICAL · 2026-07-17
- Actively Exploited SonicWall SMA1000 Zero-Days (CVE-2026-15409, CVE-2026-15410) Chained for Full Appliance Takeover Alongside Microsoft July 2026 Patch Tuesday (570 CVEs, 3 Zero-Days incl. SharePoint & AD FS EoP) — CRITICAL · 2026-07-17
- CVE-2026-50661: Windows BitLocker Security Feature Bypass 0-Day — MEDIUM · 2026-07-15
- CVE-2026-56155: Microsoft AD FS Elevation-of-Privilege Vulnerability Actively Exploited — HIGH · 2026-07-15
- Microsoft July 2026 Patch Tuesday: Two Actively Exploited Zero-Days in AD FS (CVE-2026-56155) and SharePoint (CVE-2026-56164), Plus Unpatched BitLocker Bypass (CVE-2026-50661) — CRITICAL · 2026-07-15
- CVE-2026-56164: Microsoft SharePoint Server Missing-Authentication Vulnerability Actively Exploited, Added to CISA KEV — CRITICAL · 2026-07-15
- July 2026 Patch Tuesday: Microsoft Fixes 622 CVEs Including Three Actively-Targeted Zero-Days (CVE-2026-56155 AD FS EoP, CVE-2026-56164 SharePoint EoP, CVE-2026-50661 BitLocker Bypass) — CRITICAL · 2026-07-15
- Microsoft July 2026 Patch Tuesday: 570 Flaws Fixed, 3 Zero-Days Including AD FS and SharePoint Privilege Escalation — CRITICAL · 2026-07-14
- Microsoft July 2026 Patch Tuesday: 570 Vulnerabilities Fixed, Including 2 Actively Exploited Zero-Days (CVE-2026-56164, CVE-2026-56155) — CRITICAL · 2026-07-14
- Windows 10 KB5099539 Extended Security Update Patches July 2026 Patch Tuesday Zero-Days — AD FS (CVE-2026-56155), SharePoint (CVE-2026-56164) Exploited; BitLocker (CVE-2026-50661) Publicly Disclosed — HIGH · 2026-07-14
- Microsoft July 2026 Patch Tuesday: 569 CVEs, Two Actively Exploited Zero-Days (CVE-2026-56155 AD FS EoP, CVE-2026-56164 SharePoint EoP) — CRITICAL · 2026-07-14
- Microsoft July 2026 Patch Tuesday: 570 Vulnerabilities Including Two Under Active Exploitation (CVE-2026-56155, CVE-2026-56164) — HIGH · 2026-07-14
- Microsoft July 2026 Patch Tuesday: Record 622 CVEs Include Two Actively Exploited Zero-Days in AD FS (CVE-2026-56155) and SharePoint Server (CVE-2026-56164) — CRITICAL · 2026-07-14
- Microsoft July 2026 Patch Tuesday: Record 622 Flaws Fixed, Two Zero-Days Under Active Exploitation (CVE-2026-56164, CVE-2026-56155) — CRITICAL · 2026-07-14
- Microsoft July 2026 Patch Tuesday: Two Actively Exploited Zero-Days in AD FS and SharePoint (CVE-2026-56155, CVE-2026-56164) — CRITICAL · 2026-07-14
- July 2026 Patch Tuesday: Two Actively Exploited Microsoft Zero-Days (SharePoint EoP CVE-2026-56164, AD FS EoP CVE-2026-56155) Plus SharePoint JWT Auth Bypass CVE-2026-55040 — HIGH · 2026-07-14
Sources
Enriched from CVE.org, NVD, CISA KEV, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.