# CVE-2026-63095: matrix-org Dendrite improper authorization in Matrix Client-Server API

Source: https://junglewise.ai/threats/cve-2026-63095-matrix-org-dendrite-improper-authorization-in-matrix-client  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-17. Updated: 2026-07-17  
License: CC BY 4.0 with a link back

CVE-2026-63095 · Severity: medium · CVSS 6.5 · Published 2026-07-17

Dendrite is a server implementation for the Matrix communication protocol. A security flaw allows any logged-in user to remove the email addresses or phone numbers linked to other users' accounts. An attacker can use this to disable a victim's ability to reset their password and potentially take over the victim's account by re-linking the stolen identifier to their own profile.

Technologies: [Matrix.org Dendrite](https://junglewise.ai/threats/technologies/dendrite). Vendors: [Matrix.org](https://junglewise.ai/threats/vendors/matrix-org).

## Quick answers

**Is CVE-2026-63095 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63095 being exploited in the wild.

**How severe is CVE-2026-63095?** Medium severity, with a CVSS score of 6.5, published 17 July 2026.

**Which products and versions are affected?** Matrix.org Dendrite <= 0.13.8.

**Is there a fix for CVE-2026-63095?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-63095 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-63095?** Check whether you run Matrix.org Dendrite at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An Insecure Direct Object Reference (IDOR) exists in the 'POST /_matrix/client/v3/account/3pid/delete' endpoint. While the handler authenticates the caller, it fails to verify that the 'address' and 'medium' parameters provided in the request body actually belong to the authenticated user. An attacker with a low-privileged account can exploit the 'Forget3PID' handler to remove a victim's email or MSISDN binding. By subsequently rebinding that identifier through an identity server, the attacker can hijack the homeserver's password reset flow to achieve full account takeover. The Dendrite repository was archived in November 2024, and no official patch has been released for this version.

## Affected products

- matrix-org Dendrite <= 0.13.8

## Timeline

- 2024-11-25: other: Upstream repository archived by owner
- 2026-07-17: disclosed: Vulnerability details published by researcher
- 2026-07-17: advisory: NVD and VulnCheck advisories published

## References

- [https://github.com/geo-chen/oss/blob/main/dendrite.md](https://github.com/geo-chen/oss/blob/main/dendrite.md)
- [https://www.vulncheck.com/advisories/dendrite-improper-authorization-via-post-account-3pid-delete-endpoint](https://www.vulncheck.com/advisories/dendrite-improper-authorization-via-post-account-3pid-delete-endpoint)

## Related threats

- [Matrix Dendrite improper access control in syncapi context endpoint](https://junglewise.ai/threats/cve-2026-63097-matrix-dendrite-improper-access-control-in-syncapi-context)
- [Matrix.org Dendrite SSRF in legacy media download endpoint](https://junglewise.ai/threats/cve-2026-63096-matrix-org-dendrite-ssrf-in-legacy-media-download-endpoint)