Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain low-privileged local foothold
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DeliveryInteract with Program Compatibility Assistant Service
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ExploitTrigger use-after-free race condition
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ExecutionReclaim freed object with controlled data
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ImpactExecute code as SYSTEM
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires the attacker to already have authenticated low-privileged local code execution on the Windows host (CVSS PR:L) and to interact with the Program Compatibility Assistant Service (pcasvc), the specific component containing the use-after-free. Successful exploitation is gated by a high-complexity condition (AC:H) characteristic of UAF races - the attacker must reliably reclaim the freed object with attacker-controlled memory, often requiring repeated timing-sensitive attempts. There is no remote or unauthenticated path and no user interaction is required (UI:N); the limiting factors are the mandatory local foothold and the race-condition reliability, both of which substantially raise the practical bar beyond the raw 7.0 score. |
| Impact | This is a genuine but second-tier priority. The CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.0 HIGH) describes a local-only privilege escalation requiring an attacker to already hold low-level authenticated access (PR:L) and to win a difficult race or satisfy a hard-to-control precondition (AC:H), which is typical of use-after-free flaws. The SSVC decision framework reinforces a measured posture: Exploitation is 'none' (no observed or public exploitation), Automatable is 'no' (consistent with AC:H - the UAF cannot be reliably mass-triggered), while Technical Impact is 'total' (consistent with C:H/I:H/A:H full SYSTEM compromise on success). Signals are internally consistent and point to a reliability-limited local EoP rather than a mass-exploitation threat. No CISA KEV listing and no EPSS score were provided in the input; absence of these is not evidence of safety but does mean there is no current data suggesting active or widespread exploitation. One metadata conflict exists: the input Tags include 'Denial Of Service', but the description and CVSS impact (C:H/I:H/A:H, privilege elevation) describe code-execution-grade privilege escalation, not a DoS - treat the DoS tag as likely mislabeled. Net: patch on a normal prioritized cadence as part of Patch Tuesday hygiene; it is not a drop-everything emergency absent exploitation evidence. |
| Exploit ScenarioDerived | An attacker who has already obtained standard low-privileged code execution on a Windows host (for example via a phishing payload or a compromised service account) triggers a use-after-free in the Program Compatibility Assistant Service to corrupt memory and elevate to SYSTEM. Because AC:H reflects a race or timing-dependent condition, the attacker may need multiple attempts before the dangling pointer is reclaimed with attacker-controlled data. No public exploit code has been identified at time of analysis. |
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Alert meAnalysisAIv1 – Oct 14, 2026
Local privilege escalation in Microsoft Windows targets the Program Compatibility Assistant Service (PCASvc) and affects Windows 10, Windows 11, and Windows Server 2016 through 2025, letting an attacker who already holds low-privileged local code execution corrupt freed memory and escalate to SYSTEM. The root cause is a use-after-free (CWE-416) scored 7.0, and the assigned CVSS vector (AV:L/AC:H/PR:L/UI:N) makes clear that exploitation is gated by a timing-sensitive high-complexity memory-reclamation race rather than a deterministic trigger; the attacker must already have an authenticated local foothold and must successfully reclaim the freed object with controlled data. Microsoft has released a vendor patch and CISA's SSVC assessment records no exploitation and no automatable path, so there is no public exploit identified at time of analysis and no evidence of active exploitation (no CISA KEV listing).
RemediationAI
Vendor-released patch: Microsoft has published a fixed build for every affected branch, so apply the current cumulative security update for Windows from the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69596 and verify the installed build meets or exceeds the listed thresholds (for example 10.0.26100.9711 for Windows 11 24H2, 10.0.22631.7652 for 23H2, 10.0.26200.9711 for 25H2, 10.0.20348.5761 for Server 2022, 10.0.26100.33650 for Server 2025, 10.0.14393.9612 for Server 2016/Windows 10 1607, and 10.0.17763.9376 for Server 2019/Windows 10 1809). Because exploitation requires an existing low-privileged local execution foothold, the most effective compensating controls reduce that precondition rather than the service itself: enforce WDAC or AppLocker application-control policies and least-privilege local accounts to shrink the pool of code that can reach the service, and monitor for repeated pcasvc crashes or abnormal heap activity as an exploitation indicator; the trade-off is administrative overhead and possible blocking of legitimate unsigned tooling. Disabling the Program Compatibility Assistant service entirely would remove the attack surface but degrades compatibility diagnostics and PCA prompts for legacy applications and is not a supported configuration, so it should only be considered as a last-resort temporary measure on isolated, high-value hosts. Prioritize patching on multi-user systems, RDP jump hosts, and VDI or session hosts where untrusted users already hold interactive logons, since those environments supply both the required PR:L foothold and the greatest payoff from SYSTEM escalation; the CISA SSVC assessment of no exploitation and no automatable path supports treating this as a routine Patch Tuesday item rather than an emergency out-of-band response.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 16 packages in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
PCASvc is the Windows Program Compatibility Assistant service, a SYSTEM-level component that inspects applications for legacy-OS compatibility problems and surfaces the compatibility dialogs and telemetry behind the 'Program Compatibility Assistant' experience. The vulnerability is a use-after-free (CWE-416): a heap object owned by the service is released while a stale pointer to it remains reachable, and an attacker with local code execution can attempt to reclaim that freed allocation with attacker-influenced contents before the dangling reference is dereferenced. Because the service runs at high privilege, a successful reclaim can turn the stale reference into controlled memory access within the service's context, yielding arbitrary code execution as SYSTEM from a low-privileged starting point. The high attack-complexity rating (AC:H) reflects heap grooming and race timing requirements - reliable exploitation typically demands repeated attempts and precise control of allocation patterns, which is consistent with the SSVC finding that the issue is not automatable. The CVSS scope is unchanged (S:U), so impact is confined to the host, with high confidentiality, integrity, and availability effects once the escalation succeeds.
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Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only service interaction gives AV:L; a low-privileged foothold is needed so PR:L; the UAF race makes reliable exploitation hard, hence AC:H; success yields full SYSTEM compromise so C:H/I:H/A:H.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Program Compatibility Assistant Service allows an authorized attacker to elevate privileges locally.
Executive ViewAI
A high-severity local privilege escalation vulnerability in Microsoft Windows Program Compatibility Assistant Service (PCASvc) affects Windows 10, Windows 11, and Windows Server 2016 through 2025, allowing an authenticated local attacker to raise privileges from a low-privileged foothold to full SYSTEM control. Because exploitation presupposes that an adversary has already established code execution on the endpoint, this flaw is a post-compromise escalation enabler rather than a remote entry point, and it directly threatens the integrity of the endpoint estate and any administrative credentials or domain access those machines hold. Leadership should treat it as a fleet-wide hardening obligation: unpatched endpoints could turn a contained single-host intrusion into full system control and lateral movement, though no public exploit identified at time of analysis and no evidence of active exploitation (no CISA KEV listing) indicate the near-term risk is manageable within normal patch cycles.
Apply vendor patch.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
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EUVD-2026-99894
GHSA-47w6-vrgj-542f
NVD
CVE.org
EPSS
Vulnrichment
Exploit-DB