CVE-2026-63097

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreHIGH confidence

Score 4.3 from GitHub Security Advisory published 2026-07-17. the CNA's CVSS baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 3 sources updated this weekElevated
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.3
EG Score
4.3(high)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity43% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

July 17, 2026

Last Modified

July 28, 2026

Advisory Details (2)

Auto-updated Jul 17, 2026
No patch confirmed yet.
generic

Dendrite 0.13.8 syncapi /context Endpoint Post-Leave State Exposure | Advisories | VulnCheck

https://www.vulncheck.com/advisories/dendrite-syncapi-context-endpoint-post-leave-state-exposure
generic

oss/dendrite.md at main · geo-chen/oss · GitHub

https://github.com/geo-chen/oss/blob/main/dendrite.md#finding-3-context-returns-current-room-state-to-non-members-and-left-users-history-visibility-bypass

Vendor Advisories for CVE-2026-63097(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 24× in last 7d / 37× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-30 21:34 UTCEG score recompute
  2. 2026-07-30 21:34 UTCGHSA enrichment
  3. 2026-07-30 16:28 UTCEPSS rescore
  4. 2026-07-30 01:30 UTCEPSS rescore
  5. 2026-07-30 01:30 UTCEPSS rescore
  6. 2026-07-29 23:07 UTCGHSA enrichment
  7. 2026-07-29 00:43 UTCEG score recompute
  8. 2026-07-29 00:43 UTCGHSA enrichment
  9. 2026-07-28 15:37 UTCEPSS rescore
  10. 2026-07-28 02:20 UTCEG score recompute
  11. 2026-07-28 02:20 UTCGHSA enrichment
  12. 2026-07-28 01:26 UTCEG score recompute
  13. 2026-07-28 01:25 UTCGHSA enrichment
  14. 2026-07-27 14:14 UTCEPSS rescore
  15. 2026-07-27 03:03 UTCEG score recompute
  16. 2026-07-27 03:03 UTCGHSA enrichment
  17. 2026-07-26 14:54 UTCEPSS rescore
  18. 2026-07-26 14:54 UTCEPSS rescore
  19. 2026-07-26 04:37 UTCEG score recompute
  20. 2026-07-26 04:36 UTCGHSA enrichment
  21. 2026-07-25 14:18 UTCEPSS rescore
  22. 2026-07-25 14:18 UTCEPSS rescore
  23. 2026-07-24 14:18 UTCEPSS rescore
  24. 2026-07-24 14:18 UTCEPSS rescore
  25. 2026-07-23 14:18 UTCEPSS rescore
Show 12 more
  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:22 UTCEG score recompute
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-22 14:08 UTCEPSS rescore
  5. 2026-07-21 15:25 UTCEPSS rescore
  6. 2026-07-21 15:25 UTCEPSS rescore
  7. 2026-07-20 17:08 UTCEPSS rescore
  8. 2026-07-19 14:31 UTCEPSS rescore
  9. 2026-07-19 02:29 UTCEPSS rescore
  10. 2026-07-17 18:07 UTCEG score recompute
  11. 2026-07-17 15:50 UTCEG score recompute
  12. 2026-07-17 15:49 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-63097?
CVE-2026-63097 is a medium vulnerability published on July 17, 2026. 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…
When was CVE-2026-63097 disclosed?
CVE-2026-63097 was first published in the National Vulnerability Database on July 17, 2026, with the most recent update on July 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63097 actively exploited?
CVE-2026-63097 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.4% of all scored CVEs.
What is the CVSS score of CVE-2026-63097?
CVE-2026-63097 has a CVSS v4.0 base score of 4.3 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-63097?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63097, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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