CVE-2026-55566

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
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.

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs processes attacker-controlled data from the /ext URL route in yamcs-web/src/main/webapp/projects/webapp/src/app/core/routes/extension.matcher.ts, extension.component.ts, and app.component.ts without checking registered plugin IDs before DOM rendering through innerHTML. A crafted URL can execute JavaScript when opened by a user. The script can read data available to the Yamcs web application and perform actions in the user context. This issue is fixed in versions 5.12.8 and 5.13.2.

CVSS v3
4.3
EG Score
4.3(medium)
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
20%
KEV
Not listed

Published

August 28, 2026

Last Modified

September 8, 2026

Advisory Details (5)

Auto-updated Aug 28, 2026
Patch available. Sources: github_commit, github_release, github.
github Patch Available

DOM XSS in Extension Routing · Advisory · yamcs/yamcs · GitHub

https://github.com/yamcs/yamcs/security/advisories/GHSA-9272-wg2r-7xmx
github_release Patch Available

Yamcs 5.13.2

Patch available: yamcs/yamcs yamcs-5.13.2

https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2
github_release Patch Available

Yamcs 5.12.8

Patch available: yamcs/yamcs yamcs-5.12.8

https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8
github_commit

commit ecf34a4e2ccb (yamcs/yamcs)

Fix landed in yamcs/yamcs commit ecf34a4e2ccb — awaiting tagged release

https://github.com/yamcs/yamcs/commit/ecf34a4e2ccbe085e6ceff0253595b24d5ecb4aa
github_commit

commit 8e18e279d8ce (yamcs/yamcs)

Fix landed in yamcs/yamcs commit 8e18e279d8ce — awaiting tagged release

https://github.com/yamcs/yamcs/commit/8e18e279d8ce761c21f4f67bbd06a1bff804d297

Vendor Advisories for CVE-2026-55566(1)

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

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.yamcs:yamcs-core0.29.3 ... 5.9.9 (166 versions)5.12.8—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 40× 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. 2026-09-19 01:38 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 03:25 UTCEG score recompute
  4. 2026-09-17 19:31 UTCEPSS rescore
  5. 2026-09-17 05:12 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 06:58 UTCEG score recompute
  8. 2026-09-16 05:15 UTCEPSS rescore
  9. 2026-09-15 08:45 UTCEG score recompute
  10. 2026-09-15 03:11 UTCEPSS rescore
  11. 2026-09-14 10:29 UTCEG score recompute
  12. 2026-09-13 16:47 UTCEPSS rescore
  13. 2026-09-13 12:16 UTCEG score recompute
  14. 2026-09-11 15:50 UTCEG score recompute
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-10 17:37 UTCEG score recompute
  17. 2026-09-10 09:35 UTCEPSS rescore
  18. 2026-09-09 19:24 UTCEG score recompute
  19. 2026-09-08 22:01 UTCEPSS rescore
  20. 2026-09-08 03:54 UTCEG score recompute
  21. 2026-09-07 16:01 UTCEPSS rescore
  22. 2026-09-07 05:41 UTCEG score recompute
  23. 2026-09-06 13:47 UTCEPSS rescore
  24. 2026-09-06 07:27 UTCEG score recompute
  25. 2026-09-05 09:12 UTCEG score recompute
Show 15 more
  1. 2026-09-04 10:59 UTCEG score recompute
  2. 2026-09-04 05:06 UTCEPSS rescore
  3. 2026-09-02 14:24 UTCEG score recompute
  4. 2026-09-02 14:12 UTCEPSS rescore
  5. 2026-09-01 16:07 UTCEG score recompute
  6. 2026-09-01 13:54 UTCEPSS rescore
  7. 2026-09-01 04:40 UTCEPSS rescore
  8. 2026-08-31 17:29 UTCEG score recompute
  9. 2026-08-30 19:17 UTCEPSS rescore
  10. 2026-08-30 19:13 UTCEG score recompute
  11. 2026-08-30 01:22 UTCEPSS rescore
  12. 2026-08-28 22:45 UTCEG score recompute
  13. 2026-08-28 22:09 UTCEG score recompute
  14. 2026-08-28 20:25 UTCEG score recompute
  15. 2026-08-28 18:10 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55566?
CVE-2026-55566 is a medium vulnerability published on August 28, 2026. Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs processes attacker-controlled data from the /ext URL route in yamcs-web/src/main/webapp/projects/webapp/src/app/core/routes/extension.matcher.ts, extension.component.ts, and app.component.ts without checking registered plugin…
When was CVE-2026-55566 disclosed?
CVE-2026-55566 was first published in the National Vulnerability Database on August 28, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55566 actively exploited?
CVE-2026-55566 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 80.0% of all scored CVEs.
What is the CVSS score of CVE-2026-55566?
CVE-2026-55566 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-55566?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55566, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55566

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