What is CVE-2026-56155?

CVE-2026-56155 is Active Directory Federation Services Elevation of Privilege Vulnerability. The supplied enrichment data classifies it as Access Control mapped to CWE-1220 CWE-1220.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

4 public PoC repositories reported; 0 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with Not reported where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-56155 using CVSS 7.8, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVhighAccess Controlpublic exploit

CVE-2026-56155

CVE-2026-56155 — Active Directory Federation Services Elevation of Privilege Vulnerability

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-56155 in CISA KEV with 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.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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

Published Jul 14, 2026Updated Jul 15, 2026Sources: NVD, Microsoft (CNA), CISA, FIRST EPSS, GitHub, GitHub Security Advisory

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Jul 14, 2026

EPSS

ahead of 27% of scored CVEs

Affects

Microsoft

13 products listed

CVSS base

7.8

high · 2 sources

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade Windows 10 Version 1607 to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

CISA 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.

Federal deadline Jul 28, 2026 — passed 50 days ago

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Microsoft	Windows 10 Version 1607	10.0.14393.0 to < 10.0.14393.9339	Vulnerable
Microsoft	Windows 10 Version 1809	10.0.17763.0 to < 10.0.17763.9020	Vulnerable
Microsoft	Windows Server 2012	6.2.9200.0 to < 6.2.9200.26226	Vulnerable
Microsoft	Windows Server 2012 (Server Core installation)	6.2.9200.0 to < 6.2.9200.26226	Vulnerable
Microsoft	Windows Server 2012 R2	6.3.9600.0 to < 6.3.9600.23291	Vulnerable
Microsoft	Windows Server 2012 R2 (Server Core installation)	6.3.9600.0 to < 6.3.9600.23291	Vulnerable
Microsoft	Windows Server 2016	10.0.14393.0 to < 10.0.14393.9339	Vulnerable
Microsoft	Windows Server 2016 (Server Core installation)	10.0.14393.0 to < 10.0.14393.9339	Vulnerable
Microsoft	Windows Server 2019	10.0.17763.0 to < 10.0.17763.9020	Vulnerable
Microsoft	Windows Server 2019 (Server Core installation)	10.0.17763.0 to < 10.0.17763.9020	Vulnerable
Microsoft	Windows Server 2022	10.0.20348.0 to < 10.0.20348.5386	Vulnerable
Microsoft	Windows Server 2025	10.0.26100.0 to < 10.0.26100.33158	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

High

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Local

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
7.8	CVSS 3.1	high	1.8	5.9	Microsoft (CNA), GHSA
7.8	CVSS 3.1	high	—	—	Microsoft (CNA)

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness & attack patterns

CWE-1220

Inferred from the weakness class — not observed against this CVE.

CAPEC-1 · Accessing Functionality Not Properly Constrained by ACLsCAPEC-122 · Privilege Abuse

T1574.010Hijack Execution Flow: ServicesFile Permissions Weakness

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Jul 14, 2026

Federal deadline

Jul 28, 2026

passed 50 days ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Monitor for scanner or exploit-pattern traffic after 4 public PoC repositories were reported.

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 7.8 (AV:L)
Jul 15, 2026 · NVD
Added to CISA KEV catalog
Jul 14, 2026 · CISA
Initial · CVE published
Jul 14, 2026 · NVD
Added · GHSA-p436-qch3-9m59 published (high)
Jul 14, 2026 · GitHub Security Advisory

References

8 on the record

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56155
Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56155
US Government Resource
nvd.nist.gov/vuln/detail/CVE-2026-56155
NVD, Vendor Advisory
github.com/advisories/GHSA-p436-qch3-9m59
Exploit, Third Party Advisory
msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-56155
Vendor Advisory
www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
US Government Resource
www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
US Government Resource
learn.microsoft.com/en-us/windows-server/identity/ad-fs/decommission/adfs-decommission-guide
Vendor Advisory

Coverage

1 story from the feeds we poll

The July 2026 Security Update Review
Zero Day Initiative · Jul 14, 2026

Elsewhere on this site

Microsoftevery CVE for this vendor
July 2026what else CISA listed
Access Controlsame class
CWE-1220other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-56155 is Active Directory Federation Services Elevation of Privilege Vulnerability, a high vulnerability affecting 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, Windows Server 2025 (Server Core installation) from Microsoft. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 4 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.8 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.