matrix-org dendrite up to 0.13.8 Forget3PID improper authorization

Summaryinfo

A vulnerability was found in matrix-org dendrite up to 0.13.8. It has been rated as critical. Affected by this vulnerability is an unknown functionality of the component Forget3PID Handler. The manipulation leads to improper authorization. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is documented as CVE-2026-63095. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in matrix-org dendrite up to 0.13.8 and classified as critical. This issue affects an unknown function of the component Forget3PID Handler. The manipulation with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-63095 since 07/15/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/17/2026). MITRE ATT&CK project uses the attack technique T1548.002 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• matrix-org

Name

• dendrite

Version

• 0.13.0
• 0.13.1
• 0.13.2
• 0.13.3
• 0.13.4
• 0.13.5
• 0.13.6
• 0.13.7
• 0.13.8

Support

• end of life

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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