Auth bypass in Spacebar Server
CVE-2026-70617
Spacebar Server before commit dcfd910 contains a missing authorization vulnerability that allows any authenticated attacker to add themselves to arbitrary group DM channels by sending a PUT request to the channels recipient endpoint without membership verification. Attackers can exploit the unguarded PUT /channels/{channel_id}/recipients/{user_id} handler to join private group DMs, read complete message history, post messages as a participant, and force-add third-party users without their consent.
Vulnerability class: Broken Access Control
EPSS: 0.003 (22.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Spacebar Server — versions 0
Weakness classification (CWE)
References
- disclosure@vulncheck.com (patch)
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-70617?
- CVE-2026-70617 is a high-severity vulnerability in Spacebar Server, classified under Missing Authorization. CVSS score: 8.1/10. Published 2026-08-05.
- How severe is CVE-2026-70617?
- High severity. CVSS v3 base score is 8.1 out of 10.