CVE-2026-65645: Input Validation Flaw (CVSS 4.3)

Description

Rocket.Chat in versions before 8.8.0, 8.7.1, 8.6.2, 8.5.3, 8.4.6. 8.3.8, 8.2.8, 8.1.8, and 7.10.15, the Meteor DDP methods getThreadsList and getThreadMessages accept rid / tmid as raw, untyped parameters with no schema validation. A MongoDB operator object (e.g. {"$gt": "4"}) can be substituted for a string room-id or message-id. The authorization check resolves to a room the attacker already has access to, while the downstream data query fans out across all rooms - disclosing private thread parents and their full reply content to any low-privilege authenticated user. The REST route chat.getThreadsList was patched in v5.0 (HackerOne report #1446767) by adding rid: {type:'string'} AJV validation. The equivalent DDP method was never given the same fix and remains exploitable

Is your site exposed to CVE-2026-65645?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

References

Other References

https://github.com/RocketChat/Rocket.Chat/pull/41814 https://hackerone.com/reports/3852135

Frequently Asked Questions

What is CVE-2026-65645? +

Rocket.Chat in versions before 8.8.0, 8.7.1, 8.6.2, 8.5.3, 8.4.6. 8.3.8, 8.2.8, 8.1.8, and 7.10.15, the Meteor DDP methods getThreadsList and getThreadMessages accept rid / tmid as raw, untyped parameters with no schema validation. A MongoDB operator object (e.g. {"$gt": "4"}) can be substituted for a string room-id or message-id. The authorization check resolves to a room the attacker already has access to, while the downstream data query fans out across all rooms - disclosing private thread parents and their full reply content to any low-privilege authenticated user. The REST route chat.getThreadsList was patched in v5.0 (HackerOne report #1446767) by adding rid: {type:'string'} AJV validation. The equivalent DDP method was never given the same fix and remains exploitable It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-65645? +

CVE-2026-65645 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-65645? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-84357

Improper input validation in Omnibox in Google Chrome prior to 152.0.7977.75 allowed a remote attacker leveraging social engineering to bypass …

CVE-2025-13826

Zervit's portable HTTP/web server is vulnerable to remote DoS attacks when a configuration reset request is made. The vulnerability is …

CVE-2026-62658

A security flaw was discovered in certain NETGEAR Nighthawk RAX series routers that could allow someone already logged in to …

CVE-2024-54011

Penetration Testing engineers at Amazon have discovered a flaw where the camera system fails to properly handle data supplied in …

CVE-2026-56349

n8n before version 2.10.0 contains an input validation vulnerability in the Guardrail node that allows attackers to bypass default guardrail …

CVE-2026-6409

A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. Maliciously structured …

CVE-2026-65645