Auth bypass in Matrix-Org Dendrite
CVE-2026-63095
Dendrite through 0.13.8 contains an improper authorization vulnerability in the Matrix Client-Server API that allows any authenticated local user to delete third-party identifier bindings belonging to other users by submitting an arbitrary address and medium to the account deletion endpoint without ownership verification. Attackers can exploit the unverified Forget3PID handler to remove a victim's email or MSISDN binding and subsequently rebind the address through an identity server to hijack the victim's password reset flow.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (21.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Matrix-Org Dendrite — versions 0
Weakness classification (CWE)
References
- Researcher Disclosure (technical-description, exploit)
- www.vulncheck.com/advisories/dendrite-improper-authorization-via-post-account-3… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-63095?
- CVE-2026-63095 is a medium-severity vulnerability in Matrix-Org Dendrite, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-07-17.
- How severe is CVE-2026-63095?
- Medium severity. CVSS v3 base score is 6.5 out of 10.