Auth bypass in Sdelements Lets-Chat
CVE-2026-66750
Let's Chat 0.3.0 through 0.4.8 contains a broken access control vulnerability that allows authenticated attackers to download file attachments from private and password-protected rooms they are not a member of by exploiting missing room membership checks in the file retrieval route. Attackers can enumerate adjacent MongoDB ObjectIds derived from a known file ID to recover files uploaded by other users, as the GET /files/:id/:name route in app/controllers/files.js only enforces login authentication without consulting room membership or the Room.canJoin check.
Vulnerability class: Broken Access Control
EPSS: 0.003 (18.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Sdelements Lets-chat — versions 0.3.0, 55e8833974c83559ed2cbc12bc15febeb2466254
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-66750?
- CVE-2026-66750 is a medium-severity vulnerability in Sdelements Lets-Chat, classified under Missing Authorization. CVSS score: 4.3/10. Published 2026-07-28.
- How severe is CVE-2026-66750?
- Medium severity. CVSS v3 base score is 4.3 out of 10.
- Is CVE-2026-66750 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.