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 affects matrix-org's Dendrite through version 0.13.8. The vulnerability is an improper authorization issue in the Client-Server API's Forget3PID handler. Authenticated local users can submit arbitrary addresses and mediums to the account deletion endpoint to delete third-party identifier bindings of other users without ownership verification. This enables attackers to remove victim bindings like email or MSISDN and rebind them via an identity server, facilitating hijacking of password reset flows.
Potential Impact
An attacker with authenticated local access can delete third-party identifier bindings of other users, such as email addresses or phone numbers, without authorization. This can lead to account takeover by hijacking password reset mechanisms that rely on these identifiers. The vulnerability has a CVSS 4.0 score of 7.1 (high severity), indicating significant risk if exploited.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict authenticated local user access to trusted parties only to reduce risk. Monitor vendor channels for an official fix or update addressing this authorization bypass.
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 affects matrix-org's Dendrite through version 0.13.8. The vulnerability is an improper authorization issue in the Client-Server API's Forget3PID handler. Authenticated local users can submit arbitrary addresses and mediums to the account deletion endpoint to delete third-party identifier bindings of other users without ownership verification. This enables attackers to remove victim bindings like email or MSISDN and rebind them via an identity server, facilitating hijacking of password reset flows.
Potential Impact
An attacker with authenticated local access can delete third-party identifier bindings of other users, such as email addresses or phone numbers, without authorization. This can lead to account takeover by hijacking password reset mechanisms that rely on these identifiers. The vulnerability has a CVSS 4.0 score of 7.1 (high severity), indicating significant risk if exploited.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict authenticated local user access to trusted parties only to reduce risk. Monitor vendor channels for an official fix or update addressing this authorization bypass.
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: 07/18/2026, 12:05:01 UTC
Last updated: 07/18/2026, 13:34:59 UTC
Views: 5
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