CVE-2026-63095: Authorization Bypass Through User-Controlled Key in matrix-org dendrite
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.
AI Analysis
Technical Summary
CVE-2026-63095 describes an improper authorization vulnerability in matrix-org's Dendrite (<=0.13.8) within the Matrix Client-Server API. The flaw allows any authenticated local user to submit arbitrary addresses and mediums to the account deletion endpoint's Forget3PID handler without verifying ownership. This enables deletion of third-party identifier bindings (such as email or MSISDN) belonging to other users. Attackers can exploit this to remove victim bindings and then rebind those identifiers via an identity server, facilitating hijacking of the victim's password reset process.
Potential Impact
The vulnerability enables authenticated local users to delete third-party identifier bindings of other users without authorization. This can lead to hijacking of password reset flows by rebinding the victim's email or MSISDN addresses, potentially allowing account takeover or unauthorized access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation has been documented at this time.
CVE-2026-63095: Authorization Bypass Through User-Controlled Key in matrix-org dendrite
Description
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.
CVSS v4.0
Score 7.1high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-63095 describes an improper authorization vulnerability in matrix-org's Dendrite (<=0.13.8) within the Matrix Client-Server API. The flaw allows any authenticated local user to submit arbitrary addresses and mediums to the account deletion endpoint's Forget3PID handler without verifying ownership. This enables deletion of third-party identifier bindings (such as email or MSISDN) belonging to other users. Attackers can exploit this to remove victim bindings and then rebind those identifiers via an identity server, facilitating hijacking of the victim's password reset process.
Potential Impact
The vulnerability enables authenticated local users to delete third-party identifier bindings of other users without authorization. This can lead to hijacking of password reset flows by rebinding the victim's email or MSISDN addresses, potentially allowing account takeover or unauthorized access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation has been documented at this time.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-07-15T15:45:44.601Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5b5ec72d1edb114c7fbd8e
Added to database: 07/18/2026, 11:08:55 UTC
Last enriched: 07/30/2026, 00:48:26 UTC
Last updated: 08/30/2026, 17:11:40 UTC
Views: 67
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