---
id: CVE-2026-70617
title: >-
  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 with…
summary: >-
  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 with…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-862
published: '2026-08-05'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T20:34:51.637'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-70617'
references:
  - url: >-
      https://github.com/spacebarchat/server/commit/dcfd91035e3da42abf5f32d8d86a35219225b3d4
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/spacebarchat/server/security/advisories/GHSA-g38j-78fh-jm74
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/spacebar-server-missing-authorization-via-group-dm-recipient-endpoint
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/spacebarchat/server/security/advisories/GHSA-g38j-78fh-jm74
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00413
epssPercentile: 0.32823
ingestedAt: '2026-09-16T21:05:36.833Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.