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CVE-2026-63097— Dendrite 0.13.8 syncapi /context Endpoint Post-Leave State Exposure

CVSS 4.3 · Medium EPSS 0.16% · P6

Possible ATT&CK Techniques 1AI

T1530 · Data from Cloud Storage

Affected Version Matrix 1

VendorProductVersion RangeStatus
matrix-orgdendrite≤ 0.13.8affected
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I. Basic Information for CVE-2026-63097

Vulnerability Information
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Vulnerability Title
Dendrite 0.13.8 syncapi /context Endpoint Post-Leave State Exposure
Source: NVD (National Vulnerability Database)
Vulnerability Description
Dendrite through 0.13.8 contains an improper access control vulnerability in the syncapi /context endpoint (syncapi/routing/context.go) that allows authenticated local users to access post-leave room state events by exploiting a flawed membership check that evaluates only the RoomExists field while ignoring IsInRoom, HasBeenInRoom, and Membership fields. Attackers who have left a room can call the rooms context API endpoint for a previously permitted event and receive unfiltered current room state that the /messages and /sync endpoints correctly withhold.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
授权机制不正确
Source: NVD (National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
matrix-orgdendrite 0 ~ 0.13.8 -

II. Public POCs for CVE-2026-63097

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III. Intelligence Information for CVE-2026-63097

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Vendor Advisories for CVE-2026-63097 (1)

Proof of Concept for CVE-2026-63097 (1)

Same Patch Batch · matrix-org · 2026-07-17 · 3 CVEs total

CVE-2026-630956.5 MEDIUMDendrite 0.13.8 Improper Authorization via POST account/3pid/delete Endpoint
CVE-2026-630965.8 MEDIUMDendrite 0.13.8 SSRF via Unauthenticated Legacy Media Download Endpoint

IV. Related Vulnerabilities

Same product: dendrite
Same vendor: matrix-org
Same weakness: CWE-863

V. Comments for CVE-2026-63097

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