CVE-2026-54047 LaciSynchroni CVE debrief

Who should care

Defenders responsible for Laci Synchroni deployments should assess exposure and prioritize patching to prevent user impersonation. This includes reviewing the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Why it matters

CVE-2026-54047 is a critical vulnerability in Laci Synchroni that allows an attacker to impersonate any target user and perform actions on their behalf. Defenders should prioritize patching to version 1.2.3 or later to prevent user impersonation.

• User impersonation and unauthorized actions
• Potential for lateral movement and privilege escalation

Technical summary

The vulnerability is caused by an improper authentication issue in the application's OAuth2 login flow. The application relies on client-side state by trusting the 'UID' field inside the 'Authentications' object of a user's local 'config.json' file. This allows an attacker to supply an arbitrary UID by manually editing the local file. The server fails to validate that the authenticated OAuth2 identity matches the requested UID, allowing an attacker to fully impersonate any target user and perform actions on their behalf. The issue has been resolved in version 1.2.3.

Defensive priority

Defenders should prioritize patching to version 1.2.3 or later to prevent user impersonation.

Recommended defensive actions

• Patch to version 1.2.3 or later
• Verify user authentication mechanisms
• Monitor for suspicious activity
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The vulnerability is caused by the application's reliance on client-side state, trusting the 'UID' field inside the 'Authentications' object of a user's local 'config.json' file. This allows an attacker to supply an arbitrary UID by manually editing the local file. The issue has been resolved in version 1.2.3. No known workarounds are available. Defenders should verify user authentication mechanisms and monitor for suspicious activity. The CVE record was published on 2026-09-11T17:17:10.477Z and has not been modified since then. The N

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.