CVE-2026-70617: Auth Bypass (CVSS 8.1)

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Weakness Type (CWE)

CWE-862 Missing Authorization

References

Other References

https://github.com/spacebarchat/server/commit/dcfd91035e3da42abf5f32d8d86a35219225b3d4 https://github.com/spacebarchat/server/security/advisories/GHSA-g38j-78fh-jm74 https://www.vulncheck.com/advisories/spacebar-server-missing-authorization-via-group-dm-recipient-endpoint

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-70617? +

CVE-2026-70617 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-70617? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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