Vulnerability · Published Aug 5, 2026 · Assigned by VulnCheck

CVE-2026-70617Spacebar Server Missing Authorization via Group DM Recipient Endpoint

High 8.1

In plain English

A high-severity missing authorization in Spacebar Server from Spacebar Server. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities).

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.4%top 64.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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 products (as reported)

Vendor	Product	Versions
Spacebar Server	Spacebar Server	0 – through dcfd91035e3da42abf5f32d8d86a35219225b3d4

Weakness: CWE-862 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

References

GitHub Security Advisory (GHSA-g38j-78fh-jm74) vendor-advisory
Patch Commit patch
https://www.vulncheck.com/advisories/spacebar-server-missing-authorization-via-group-dm-recipient-endpoint third-party-advisory