matrix-org dendrite up to 0.13.8 Context Endpoint context.go roomexists access control

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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3.3$0-$5k2.27+

Summaryinfo

A vulnerability was found in matrix-org dendrite up to 0.13.8. It has been rated as problematic. This vulnerability affects unknown code of the file syncapi/routing/context.go of the component Context Endpoint. This manipulation of the argument roomexists causes access control. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is registered as CVE-2026-63097. The attack needs to be launched locally. No exploit is available.

Detailsinfo

A vulnerability classified as problematic was found in matrix-org dendrite up to 0.13.8. Affected by this vulnerability is an unknown function of the file syncapi/routing/context.go of the component Context Endpoint. The manipulation of the argument roomexists with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-63097 since 07/15/2026. The exploitation appears to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

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

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

Name

Version

Support

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.3
VulDB Meta Temp Score: 3.3

VulDB Base Score: 3.3
VulDB Temp Score: 3.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

07/15/2026 CVE reserved
07/17/2026 +2 days Advisory disclosed
07/17/2026 +0 days VulDB entry created
07/17/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Not defined

CVE: CVE-2026-63097 (🔒)
GCVE (CVE): GCVE-0-2026-63097
GCVE (VulDB): GCVE-100-379855

Entryinfo

Created: 07/17/2026 18:25
Changes: 07/17/2026 18:25 (55)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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