CVE-2026-56845 Rocket.Chat CVE debrief

Who should care

Defenders responsible for Rocket.Chat deployments, particularly those using CustomSounds storage with FileSystem configuration, should assess exposure and implement compensating controls.

Why it matters

CVE-2026-56845 is a high-severity vulnerability in Rocket.Chat's CustomSounds storage feature, allowing for arbitrary file reading. Defenders should prioritize verifying exposure and implementing compensating controls.

• Verify exposure and implement compensating controls to prevent arbitrary file reading
• Monitor for suspicious activity and implement logging and exception tracking to detect potential exploitation
• Restrict access to /custom-sounds/ to prevent unauthorized file access

Technical summary

An unauthenticated path traversal (LFI) vulnerability exists under /custom-sounds/ when CustomSounds storage is configured to FileSystem. By including ../ sequences in the request path, an attacker can read arbitrary files outside the base directory. This vulnerability allows for potential data breaches and unauthorized access to sensitive information. Defenders should prioritize verifying exposure and implementing compensating controls to prevent exploitation. The vulnerability is highly severe, with a CVSS score of 7.5.

Defensive priority

Defenders should prioritize verifying exposure and implementing compensating controls, as the vulnerability allows for arbitrary file reading.

Recommended defensive actions

• Verify exposure by checking if CustomSounds storage is configured to FileSystem
• Implement compensating controls, such as restricting access to /custom-sounds/
• Monitor for suspicious activity and implement logging and exception tracking
• Review vendor guidance for potential updates or patches
• Conduct asset inventory to identify potentially affected systems
• Plan for rollback or change windows if remediation is needed
• Track exceptions and retest remediated assets

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but do not specify affected versions or remediation steps. The vulnerability was disclosed on 2026-08-04 and has not been modified since then. There are no known exploit details publicly available. Defenders should verify exposure and implement compensating controls. Evidence is limited to CVE and NVD entries.

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.