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Unity Parsec CVE-2026-54424

| EUVDEUVD-2026-41655 HIGH
Incorrect Use of Privileged APIs (CWE-648)
2026-07-04 mitre GHSA-f445-7g93-34v9
8.4
CVSS 3.1 · Vendor: mitre
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Log in as unprivileged local Windows user
  2. Delivery
    Set attacker-controlled AppData environment variable
  3. Exploit
    Trigger parsecd.exe launch as NT AUTHORITY\SYSTEM
  4. Execution
    SYSTEM process resolves user-controlled paths
  5. Impact
    Execute code as SYSTEM and take over host

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V6 - Authentication Incorrect use of privileged APIs
Exploitation Conditions

Requires local, interactive access to a Windows host running Unity Parsec at or below v2026-05-04.0 as a normal (unprivileged) user; the attacker must be able to set/control the AppData environment variable in their own session and induce an instance of parsecd.exe to launch in the NT AUTHORITY\SYSTEM context. Limiting factors: exploitation is local-only (no network vector), so remote attackers cannot trigger it, and it depends on the vulnerable Parsec Windows host being installed and reachable by a logged-in user - hosts upgraded to 150-104a or not running the Parsec daemon are not exploitable, and single-user endpoints with no untrusted local account are low practical risk.

Impact

The published CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, base 8.4) captures the full SYSTEM-compromise impact but is optimistic on privileges: this is a local elevation-of-privilege issue, so the attacker must already be a logged-in user on the host, which is more honestly modeled as PR:L than PR:N - flag this PR:N-versus-local-EoP tension when triaging. There is no remote vector (AV:L), no user interaction beyond the attacker's own actions, and complexity is low. No EPSS probability and no KEV listing were provided, so there is no signal of mass or automated exploitation; however, a named GitHub repository plus a detailed researcher blog mean working exploit knowledge is public, raising practical risk on multi-user, RDP, or kiosk Windows hosts where untrusted users can obtain a shell. Net assessment: a credible local privilege-escalation priority where Parsec runs on shared systems, but only low-to-moderate concern on single-user endpoints because it cannot be triggered remotely or without local access.

Exploit ScenarioDerived

A standard (non-admin) user logged into a shared Windows workstation that has Parsec installed sets the AppData environment variable to a directory they control, then triggers the code path that spawns parsecd.exe as NT AUTHORITY\SYSTEM. The SYSTEM process resolves attacker-controlled paths from that AppData value, letting the user execute code or load resources as SYSTEM and take over the machine. Publicly available exploit code (a dedicated GitHub repository and researcher blog) lowers the skill needed to reproduce this.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 04, 2026

Local privilege escalation in Unity Parsec for Windows (all builds through v2026-05-04.0) lets an unprivileged local user coerce an instance of parsecd.exe to run as NT AUTHORITY\SYSTEM while honoring a user-controlled AppData environment variable, allowing the attacker to redirect the privileged process to resources under their control and gain SYSTEM. The flaw is a CWE-648 misuse of privileged APIs; publicly available exploit code exists (a dedicated CVE GitHub repository and a researcher write-up), and it is fixed in Parsec for Windows 150-104a. It is not listed in CISA KEV and no EPSS score was supplied, so there is no evidence of widespread active exploitation.

RemediationAI

Vendor-released patch: Parsec for Windows version 150-104a - upgrade every Windows host running Parsec to this build or later, per the vendor advisory at https://support.parsec.app/hc/en-us/articles/50612943726612-CVE-2026-54424. Until patched, reduce exposure by limiting interactive/local logon on machines where the privileged Parsec host runs (the flaw requires local access), accepting the trade-off of reduced shared-host convenience; where feasible restrict Parsec host installs to single-trusted-user systems and avoid running the host on multi-user, RDP, or kiosk endpoints where untrusted users can get a shell. As a detection stopgap, monitor for unexpected parsecd.exe instances running as NT AUTHORITY\SYSTEM and for anomalous AppData values in the SYSTEM context. These are compensating controls only and do not remove the flaw, so upgrading to 150-104a remains the definitive fix.

Affected VersionsENISA

Parsec 0 ≤v2026-05-04.0

Affects your stack

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Technical ContextAI · show details

Parsec is a low-latency remote desktop / game-streaming client owned by Unity; on Windows it ships a privileged host component and the parsecd.exe process. The root cause is CWE-648 (Incorrect Use of a Privileged API): a code path allows parsecd.exe to execute in the SYSTEM security context while still trusting the per-user AppData environment variable, which any interactive user can set. Because AppData normally points into the user's own profile, a SYSTEM-level process that resolves paths (config, data files, or other resources) relative to that variable can be steered to attacker-controlled locations, collapsing the trust boundary between an unprivileged user and SYSTEM. The affected component is identified by CPE cpe:2.3:a:unity:parsec:*:*:*:*:*:*:*:* on Windows hosts.

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Severity by source

Vendor (mitre) PRIMARY 8.4 HIGH
AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Local elevation of privilege requires an already-authenticated low-privileged user (PR:L, AV:L), no interaction, and yields full SYSTEM compromise (C:H/I:H/A:H).

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

An Incorrect Use of Privileged APIs vulnerability in Unity Parsec on Windows hosts leads to a potential Elevation of Privilege. This issue affects Parsec through v2026-05-04.0. The patched version is Parsec for Windows version 150-104a. A user can generate a situation where there is an instance of parsecd.exe running as NT AUTHORITY\SYSTEM with a user-controlled value of the AppData environment variable.

Executive ViewAI

Why It Matters

Parsec for Windows contains a local privilege escalation vulnerability (CVE-2026-54424, CVSS 8.4) that allows unprivileged users to gain SYSTEM-level access. While publicly available exploit code exists, this vulnerability is not listed in CISA's known exploited vulnerabilities catalog, indicating limited evidence of widespread active exploitation. Organizations must patch to eliminate the risk of insiders or attackers with local access gaining administrative control of Windows systems.

Business Impact: High
Compensating Controls

Vendor-released patch: Parsec for Windows 150-104a

Threat Intelligence Overview

EPSS Score
0.2%
Top 84% exploitable
Prevalence
Medium
popular remote-desktop/game-streaming client, common but not on every host
Social Media
3
Sightings
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment CIRCL GitHub VulDB

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.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

42
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +42
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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