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Full vulnerability report · 2026
CVE-2026-45487High confidence

Windows Program Compatibility Assistant Service Elevation of Privilege Vulnerability

Microsoft · Windows 10 Version 21H2

7.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
Optional official sources

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

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

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-2026-35673

No EUVD known-exploited evidence

Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

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
7.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

What

Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

What

Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through local access may attempt exploitation with low privileges. 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 → Time-of-check Time-of-use (TOCTOU) Race Condition → gain additional privileges
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
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-367 ↗

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

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:L/UI:N/S:U/C:H/I:H/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.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major 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.
Privilege escalationCWE-367
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-35673Official EUVD mapping

Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.

Official EUVD record
BSI · German · WID-SEC-W-2026-1849Microsoft Windows: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in verschiedenen Versionen von Microsoft Windows und Microsoft Windows Server ausnutzen, um Administratorrechte zu erlangen, beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren und offenzulegen oder Spoofing-Angriffe durchzuführen.

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0728Multiples vulnérabilités dans Microsoft Windows

é Microsoft Windows CVE-2026-44807 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44808 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44809 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44810 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44811 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44812 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44813 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44814 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-44815 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45487 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45490 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45491 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45586 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45588 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45591 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45592 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45593 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45594 du 09 juin 2026 Bulletin de sécurité Microsoft Windows CVE-2026-45595 du 09 juin 2026 Bul

Official advisory
NCSC-NL · Dutch · NCSC-2026-0181Kwetsbaarheden verholpen in Microsoft Windows

A TOCTOU race condition vulnerability in the Program Compatibility Assistant Service allows an authorized local attacker to escalate privileges by exploiting timing discrepancies during resource access.

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.
Fix not verified
Affected
10.0.19044.0 < 10.0.19044.7417; 10.0.19045.0 < 10.0.19045.7417; 10.0.22631.0 < 10.0.22631.7219; 10.0.26100.0 < 10.0.26100.8655; 10.0.26200.0 < 10.0.26200.8655; 10.0.28000.0 < 10.0.28000.2269; 10.0.20348.0 < 10.0.20348.5256
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 9 Jun 2026 · Last source change 25 Aug 2026, 22:43 UTC · CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

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-2026-35673
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceOther authority
NVD statusNVD enriched

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

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-35673↗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-2026-45487 · cve.blacktree.nl