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Full vulnerability report · 2021
CVE-2021-42303High confidence

Azure RTOS Elevation of Privilege Vulnerability

Microsoft · Azure Real Time Operating System

6.6MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.86% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft Azure Real Time Operating System and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-29278

No EUVD known-exploited evidence

Azure RTOS Elevation of Privilege Vulnerability

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
6.6 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Azure RTOS Elevation of Privilege Vulnerability

What

Azure RTOS Elevation of Privilege Vulnerability

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may gain additional privileges.

What

Azure RTOS Elevation of Privilege Vulnerability

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may gain additional privileges.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Improper Privilege Management → gain additional privileges
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-269 ↗

CWE-269: Improper Privilege Management. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H/E:U/RL:O/RC:C

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedPrivilege escalationCWE-269
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2021-29278Official EUVD mapping

Azure RTOS Elevation of Privilege Vulnerability

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20211117Security Bulletin 17 Nov 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 17 Nov 2021, published on 17 November 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-863Multiples vulnérabilités dans les produits Microsoft

d?id=CVE-2021-41375 Référence CVE CVE-2021-41376 https://www.cve.org/CVERecord?id=CVE-2021-41376 Référence CVE CVE-2021-42277 https://www.cve.org/CVERecord?id=CVE-2021-42277 Référence CVE CVE-2021-42292 https://www.cve.org/CVERecord?id=CVE-2021-42292 Référence CVE CVE-2021-42296 https://www.cve.org/CVERecord?id=CVE-2021-42296 Référence CVE CVE-2021-42298 https://www.cve.org/CVERecord?id=CVE-2021-42298 Référence CVE CVE-2021-42300 https://www.cve.org/CVERecord?id=CVE-2021-42300 Référence CVE CVE-2021-42301 https://www.cve.org/CVERecord?id=CVE-2021-42301 Référence CVE CVE-2021-42302 https://www.cve.org/CVERecord?id=CVE-2021-42302 Référence CVE CVE-2021-42303 https://www.cve.org/CVERecord?id=CVE-2021-42303 Référence CVE CVE-2021-42304 https://www.cve.org/CVERecord?id=CVE-2021-42304 Référence CVE CVE-2021-42305 https://www.cve.org/CVERecord?id=CVE-2021-42305 Référence CVE CVE-2021-42316 https://www.cve.org/CVERecord?id=CVE-2021-42316 Référence CVE CVE-2021-42319 https://www.cve.org/CVERecord?id=CVE-2021-42319 Référence CVE CVE-2021-42321 https://www.cve.org/CVERecord?id=CVE-2021-42321 Référence CVE CVE-2021-42322 https://www.cve.org/CVERecord?id=CVE-2021-42322 Référence CVE CVE-2021-42323 https://www.cve.org/CVERecord?id=CVE-2021-42323 Référence CVE CVE-2021-43208 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-004237Azure RTOS における権限を昇格される脆弱性

Azure RTOS には、権限を昇格される脆弱性が存在します。 本脆弱性は、CVE-2021-42302 および CVE-2021-42303 とは異なる脆弱性です。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-004236Azure RTOS における権限を昇格される脆弱性

Azure RTOS には、権限を昇格される脆弱性が存在します。 本脆弱性は、CVE-2021-42302 および CVE-2021-42304 とは異なる脆弱性です。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-004235Azure RTOS における権限を昇格される脆弱性

Azure RTOS には、権限を昇格される脆弱性が存在します。 本脆弱性は、CVE-2021-42303 および CVE-2021-42304 とは異なる脆弱性です。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5435MS 11월 보안 위협에 따른 정기 보안 업데이트 권고

e Protection Engine 긴급 원격 코드 실행 MS 업데이트 페이지 참고 [4] [참고 사이트] [1] (한글) https://portal.msrc.microsoft.com/ko-kr/security-guidance [2] (영문) https://portal.msrc.microsoft.com/en-us/security-guidance [3] https://msrc.microsoft.com/update-guide/releaseNote/2021-Nov [4] https://msrc.microsoft.com/update-guide o 취약점 요약 정보 제품 카테고리 CVE 번호 CVE 제목 3D Viewer CVE-2021-43209 3D 뷰어 원격 코드 실행 취약성 3D Viewer CVE-2021-43208 3D 뷰어 원격 코드 실행 취약성 Azure CVE-2021-41373 FSLogix Information Disclosure Vulnerability Azure RTOS CVE-2021-42323 Azure RTOS Information Disclosure Vulnerability Azure RTOS CVE-2021-42304 Azure RTOS Elevation of Privilege Vulnerability Azure RTOS CVE-2021-42303 Azure RTOS Elevation of Privilege Vulnerability Azure RTOS CVE-2021-42302 Azure RTOS Elevation of Privilege Vulnerability Azure RTOS CVE-2021-42301 Azure RTOS Information Disclosure Vulnerability Azure RTOS CVE-2021-26444 Azure RTOS Information Disclosure Vulnerability Azure Sphere CVE-2021-42300 Azure Sphere Tampering Vulnerability Azure Sphere CVE-2021-41376 Azure Sphere 정보 유출 취약성 Azure Sphere CVE-2021-41375 Azure Sphere 정보 유출 취약성 Azure Sphere CVE-2021-41374 Azure Sphere Information Disclosure Vulnerability Microsoft Dynamics CVE-2021-42316 Microsoft Dynamics 365(온-프레미스) 원격 코드 실행 취약성 Microsoft Edge (Chromium-d) in IE Mode CVE-2021-41351 Mi

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Azure Real Time Operating System: 6.0.0 < 6.1.9
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 10 Nov 2021 · Last source change 19 Aug 2026, 16:27 UTC · CWE-269 · Improper Privilege Management

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-29278
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: portal.msrc.microsoft.com/CVE-2021-42303; removed patch: msrc.microsoft.com/CVE-2021-42303; removed remediation: msrc.microsoft.com/CVE-2021-42303.
    Before
    patch: msrc.microsoft.com/CVE-2021-42303 · patch: portal.msrc.microsoft.com/CVE-2021-42303 · remediation: msrc.microsoft.com/CVE-2021-42303
    After
    patch: portal.msrc.microsoft.com/CVE-2021-42303 · remediation: portal.msrc.microsoft.com/CVE-2021-42303
    portal.msrc.microsoft.com ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2021-42303; added remediation: msrc.microsoft.com/CVE-2021-42303; removed remediation: portal.msrc.microsoft.com/CVE-2021-42303.
    Before
    patch: portal.msrc.microsoft.com/CVE-2021-42303 · remediation: portal.msrc.microsoft.com/CVE-2021-42303
    After
    patch: msrc.microsoft.com/CVE-2021-42303 · patch: portal.msrc.microsoft.com/CVE-2021-42303 · remediation: msrc.microsoft.com/CVE-2021-42303
    msrc.microsoft.com ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-29278↗Patch or update reference↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-42303 · cve.blacktree.nl