Improper Authorization in Dendrite Affecting Matrix Client-Server API
CVE-2026-63095

7.1HIGH

Key Information:

Vendor

Matrix-org

Status
Dendrite
Vendor
CVE Published:
17 July 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-63095?

Dendrite versions up to 0.13.8 exhibit an improper authorization vulnerability within the Matrix Client-Server API, allowing an authenticated user to delete third-party identifier bindings of other users. By exploiting the flawed Forget3PID handler, attackers can submit arbitrary addresses and media to the account deletion endpoint, bypassing necessary ownership checks. This can enable the removal of a victim’s email or MSISDN binding, allowing the attacker to rebind these identifiers via an identity server, potentially hijacking password reset processes for the affected users.

Affected Version(s)

dendrite 0 <= 0.13.8

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-63095 - Proof of Concept

References

https://github.com/geo-chen/oss/blob/main/dendrite.md#fin...
technical-descriptionexploit
https://www.vulncheck.com/advisories/dendrite-improper-au...
third-party-advisory

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

George Chen
.