CVE-2026-78547 Overview
CVE-2026-78547 is an out-of-bounds write vulnerability [CWE-787] affecting Citrix Workspace app for Windows. The flaw allows a local attacker with low privileges and physical access to write outside allocated memory boundaries. Successful exploitation can compromise the integrity and availability of the affected endpoint. Citrix documented the issue in security bulletin CTX697034 alongside CVE-2026-78546.
The vulnerability affects Citrix Workspace app for Windows versions prior to 2603.11 Current Release (CR), prior to 2507.1 LTSR CU3, and prior to LTSR 2607.
Critical Impact
A local attacker with physical access and low privileges can trigger an out-of-bounds write in Citrix Workspace app, leading to memory corruption that impacts integrity and availability on the affected Windows endpoint.
Affected Products
- Citrix Workspace app for Windows before 2603.11 Current Release (CR)
- Citrix Workspace app for Windows before 2507.1 LTSR CU3
- Citrix Workspace app for Windows before LTSR 2607
Discovery Timeline
- 2026-09-11 - CVE-2026-78547 published to the National Vulnerability Database (NVD)
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-78547
Vulnerability Analysis
The vulnerability is an out-of-bounds write condition in Citrix Workspace app for Windows. The application writes data past the bounds of an allocated buffer, corrupting adjacent memory structures. This memory corruption can alter program state, overwrite control data, or destabilize the process. The impact is limited to the local endpoint and requires physical access along with low-level user privileges to trigger.
Citrix has not published detailed exploitation mechanics in the public advisory. The issue affects both the Current Release and Long Term Service Release (LTSR) branches of the Windows client.
Root Cause
The root cause is classified under [CWE-787] Out-of-bounds Write. The affected component in Citrix Workspace app fails to properly validate buffer boundaries when writing data. Missing bounds checks allow attacker-controlled input to overwrite memory beyond the target buffer. This class of defect commonly stems from incorrect length calculations, missing input validation, or unsafe use of copy operations.
Attack Vector
Exploitation requires physical access to the target Windows host running a vulnerable Citrix Workspace app version. The attacker must already possess low-privileged access on the endpoint. No user interaction is required during exploitation. The attack complexity is high, which indicates that specific conditions must be met for reliable exploitation. Successful exploitation impacts integrity and availability but does not expose confidential data directly.
No public proof-of-concept code, exploit modules, or reports of exploitation in the wild are currently available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2026-78547
Indicators of Compromise
- Unexpected crashes or Windows Error Reporting (WER) entries generated by Citrix Workspace app processes such as wfica32.exe or SelfServicePlugin.exe.
- Anomalous child processes spawned by Citrix Workspace components on endpoints where physical access was recorded.
- Registry or file modifications under %ProgramFiles(x86)%\Citrix\ICA Client that do not correspond to authorized updates.
Detection Strategies
- Inventory installed Citrix Workspace app versions across the fleet and flag hosts running builds earlier than 2603.11, 2507.1 LTSR CU3, or LTSR 2607.
- Correlate physical-access events (console logons, kiosk sessions, unattended workstations) with Citrix Workspace process crashes.
- Monitor endpoint telemetry for memory corruption signals, such as access violations and exception codes originating from Citrix Workspace binaries.
Monitoring Recommendations
- Forward Windows Application and Security event logs to a centralized SIEM or data lake for correlation with endpoint crash telemetry.
- Track patch compliance for Citrix Workspace app using software asset management tooling and alert on drift.
- Enable behavioral monitoring on user endpoints to detect post-exploitation activity following process compromise, including unexpected token manipulation or privilege changes.
How to Mitigate CVE-2026-78547
Immediate Actions Required
- Upgrade Citrix Workspace app for Windows to 2603.11 Current Release, 2507.1 LTSR CU3, or LTSR 2607 or later, matching the branch deployed in your environment.
- Prioritize patching on shared, kiosk, and unattended workstations where physical access risk is highest.
- Restrict physical access to endpoints running Citrix Workspace app through facility controls and workstation locking policies.
Patch Information
Citrix has released fixed builds addressing CVE-2026-78547. Refer to the Citrix Workspace app for Windows Security Bulletin CTX697034 for the complete list of fixed versions and download links. Deploy the upgrade through standard software distribution channels and validate the installed version reports at or above the fixed baseline.
Workarounds
- No vendor-supplied workarounds are documented in the Citrix advisory; upgrading to a fixed version is the recommended remediation.
- Enforce least-privilege on end-user accounts to reduce the attacker's starting foothold on Windows endpoints.
- Apply screen locking, BitLocker, and BIOS/UEFI password controls to raise the barrier for physical-access attacks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
