Authenticated state disclosure via incomplete membership check
Published Jul 17, 2026 · Updated Jul 17, 2026
Incorrect authorization in Dendrite 0.13.8 and earlier allows remote authenticated users to read post-leave room state via /context. The syncapi/routing/context.go handler checks only RoomExists, ignores membership results, and returns CurrentState without history filtering. A user who left a shared-visibility private room needs an event previously permitted to that account; the response exposes later topics and member joins.
Summary
What happened
Incorrect authorization in Dendrite 0.13.8 and earlier allows remote authenticated users to read post-leave room state via /context. The syncapi/routing/context.go handler checks only RoomExists, ignores membership results, and returns CurrentState without history filtering. A user who left a shared-visibility private room needs an event previously permitted to that account; the response exposes later topics and member joins.
The record
- CVE
- CVE-2026-63097
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- Matrix.org Foundation
- Product
- Dendrite
- Classifications
- CWE-863, T1213
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=0.13.8
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Dendrite /context post-leave state disclosure PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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