🛡️ CVE-2026-63097

🟡 CVSS 4.3 — Medium ✅ No Known Exploit CWE-863 NVD
4.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

Weakness class

CVE-2026-63097 is classified as CWE-863: Incorrect Authorization. An authorisation check runs but reaches the wrong conclusion, permitting actions it should refuse.

Affected software

CVE-2026-63097 is recorded against 1 package.

  • unknown

Timeline and source

Published on 17 July 2026 and last revised on 23 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
www.vulncheck.com

Details

Severity MEDIUM
CVSS Score 4.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CWE CWE-863
Public Exploit ✅ No
Source NVD
Published 2026-07-17
Updated 2026-08-11
Modified 2026-07-23
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

Similar Threats

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