cbcvebase.
CVE-2026-56155
published 2026-07-14

CVE-2026-56155: Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.

PriorityP184high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
KEVITW
CISA Known Exploited Vulnerabilitydue 2026-07-28
Exploited in the wild
EPSS
0.38%
30.3th percentile
Insufficient granularity of access control in Active Directory Federation Services (AD FS) allows an authorized attacker to elevate privileges locally.

Affected

15 ranges
VendorProductVersion rangeFixed in
microsoftwindows_10_1607< 10.0.14393.933910.0.14393.9339
microsoftwindows_10_1809< 10.0.17763.902010.0.17763.9020
microsoftwindows_10_version_1607>= 10.0.14393.0 < 10.0.14393.933910.0.14393.9339
microsoftwindows_10_version_1809>= 10.0.17763.0 < 10.0.17763.902010.0.17763.9020
microsoftwindows_server_2012
microsoftwindows_server_2012>= 6.2.9200.0 < 6.2.9200.262266.2.9200.26226
microsoftwindows_server_2012_r2>= 6.3.9600.0 < 6.3.9600.232916.3.9600.23291
microsoftwindows_server_2016< 10.0.14393.933910.0.14393.9339
microsoftwindows_server_2016>= 10.0.14393.0 < 10.0.14393.933910.0.14393.9339
microsoftwindows_server_2019< 10.0.17763.902010.0.17763.9020
microsoftwindows_server_2019>= 10.0.17763.0 < 10.0.17763.902010.0.17763.9020
microsoftwindows_server_2022< 10.0.20348.538610.0.20348.5386
microsoftwindows_server_2022>= 10.0.20348.0 < 10.0.20348.538610.0.20348.5386
microsoftwindows_server_2025< 10.0.26100.3315810.0.26100.33158
microsoftwindows_server_2025>= 10.0.26100.0 < 10.0.26100.3315810.0.26100.33158

Detection & IOCsextracted from sources · hover to see the quote

  • CVE-2026-56155 is an Active Directory Federation Services (AD FS) insufficient granularity of access control vulnerability allowing local privilege escalation; it is confirmed actively exploited in the wild and listed in CISA KEV with a remediation due date of 2026-07-28.
  • CVE-2026-56155 carries a CVSS score of 7.8 and has been flagged as actively exploited; prioritize patching AD FS deployments immediately, especially internet-facing instances.
  • CISA has added CVE-2026-56155 to its Known Exploited Vulnerabilities catalog; Federal Civilian Executive Branch agencies must apply fixes by 2026-07-28. Monitor AD FS environments for unauthorized privilege escalation activity.
  • The official Microsoft patch guidance and advisory for CVE-2026-56155 is available at the MSRC update guide; use this as the authoritative source for patch verification and forensic triage requirements per BOD 26-04.
  • ·The vulnerability requires an already-authorized (authenticated) attacker to exploit; the privilege escalation is local, not remote. Attack surface is limited to users with existing access to the AD FS system.

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vulncheck7.8HIGH
cisa7.8HIGH
CVEs like this are exactly what “Exploited This Week” covers.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.