CVE-2026-70617

Spacebar Server Missing Authorization via Group DM Recipient Endpoint

HIGH
8.1
CVSS Score
Published: August 5, 2026 at 07:53 PM UTC
Updated: September 16, 2026 at 08:54 PM UTC
1 product affected across 1 vendorSpacebar Server

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Severity
HIGH8.1
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ dcfd91035e3da42abf5f32d8d86a35219225b3d4

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-862

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