CVE-2026-111384 nezhahq CVE debrief

Who should care

Defenders and security teams using Nezha for monitoring should assess their exposure and potential impact, especially in environments with file manager WebSocket endpoint access. They should prioritize verifying exposure, assessing potential impact, and implementing necessary mitigations.

Why it matters

CVE-2026-111384 is a high-severity vulnerability in Nezha 1.0.0 before 2.3.15, allowing authenticated users to cause memory exhaustion via an unbounded WebSocket endpoint. Defenders should prioritize verifying exposure, assessing potential impact, and implementing necessary mitigations.

• Potential OOM kills leading to dropped agent monitoring
• Verification of Nezha version and exposure required
• Implementation of SetReadLimit for fmStream necessary
• Restricting access to file manager WebSocket endpoint recommended

Technical summary

The Nezha dashboard file manager WebSocket endpoint is vulnerable to memory exhaustion due to an unbounded message size. Authenticated users with file manager scopes can send oversized binary messages to /api/v1/ws/file/:id, triggering an OOM kill that drops all agent monitoring. The vulnerability is caused by the fmStream not calling SetReadLimit, leaving message size unbounded. This allows an attacker to send an oversized binary message to /api/v1/ws/file/:id, triggering an OOM kill. Defenders should prioritize verifying exposure and assessing potential impact, especially in environments using Nezha for monitoring.

Defensive priority

Defenders should prioritize verifying exposure and assessing potential impact, especially in environments using Nezha for monitoring.

Recommended defensive actions

• Verify Nezha version and assess exposure
• Restrict access to file manager WebSocket endpoint
• Implement SetReadLimit for fmStream
• Monitor for potential OOM kills and adjust configurations
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability is caused by the fmStream not calling SetReadLimit, leaving message size unbounded. This allows an attacker to send an oversized binary message to /api/v1/ws/file/:id, triggering an OOM kill.

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.