CVE-2026-42901
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedOrigin validation error in Microsoft Entra ID allows an unauthorized attacker to elevate privileges over a network.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceAn origin validation vulnerability in Microsoft Entra ID allows unauthorized network attackers to elevate privileges. The flaw appears to involve improper validation of request origins in the authentication flow, potentially enabling attackers to bypass identity verification mechanisms.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Review Entra ID sign-in logs for anomalous authentication attemptsNavigate to Microsoft Entra admin center > Monitor > Sign-in logs. Filter for unusual IP addresses, locations, or authentication methods. Look for successful authentications originating from unexpected or spoofed origins.Affected if Sign-in events show authentication success from origins that do not match expected client application or IP ranges
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Examine Conditional Access policies for origin-based controlsGo to Microsoft Entra admin center > Protect > Conditional Access > Policies. Review policies to verify if any rely on origin or network location claims that could be bypassed.Affected if Conditional Access policies explicitly trust origin headers without additional verification layers
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Audit Enterprise Application registrations for cross-origin configurationNavigate to Microsoft Entra admin center > Applications > Enterprise applications. Select each application and review the Authentication settings under the Properties panel. Check for overly permissive Redirect URIs or origin AllowLists.Affected if Enterprise applications have Redirect URIs or allowed origins set to wildcard (*) or untrusted domains
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Check for unexpected privilege escalation in audit logsNavigate to Microsoft Entra admin center > Monitor > Audit logs. Filter by Category = 'UserManagement' and Activity = 'Add user to role' or similar privilege modification operations. Look for changes made from unusual origins or IP addresses.Affected if Audit logs show administrative role assignments or privilege escalation events initiated from unexpected origins or without proper user authentication context
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Verify token issuance and validation configurationReview the Token configuration under App registrations > Your app > Token configuration. Check if the access tokens or ID tokens contain claims that could be manipulated based on origin spoofing.Affected if Token claims rely solely on origin information without additional validation such as token binding or issuer verification
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Review API permissions and consented applicationsNavigate to Microsoft Entra admin center > Applications > Enterprise applications > Consent and permissions. Examine recent consent grants for suspicious or unexpected applications that may be leveraging origin bypass.Affected if New application consents appear from applications with suspicious origins or that were not initiated by legitimate users
A user is affected if their Entra ID environment shows sign-in events, audit logs, or configuration changes indicating that authentication or authorization was bypassed through manipulated origin headers, or if Conditional Access and application authentication settings rely on origin validation without additional safeguards.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataMonitor Microsoft Security Response Center for official patches; implement conditional access policies and MFA as defense-in-depth while awaiting vendor remediation.
- Consultation4.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,152.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-42901 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-42901 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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