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.
CVE-2026-55566
MEDIUMPre-NVD 4.34.3Elevated
EchelonGraph scoreLOW confidence
This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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: secondary
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.
- CVSS v3
- 4.3
- EG Score
- 4.3(low)
- 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 computedSeverity43% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 19%
- KEV
- Not listed
Published
August 28, 2026
Last Modified
August 28, 2026
Advisory Details (5)
Auto-updated Aug 28, 2026Patch 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-7xmxgithub_release Patch Available
Yamcs 5.13.2
Patch available: yamcs/yamcs yamcs-5.13.2
https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2github_release Patch Available
Yamcs 5.12.8
Patch available: yamcs/yamcs yamcs-5.12.8
https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8github_commit
commit ecf34a4e2ccb (yamcs/yamcs)
Fix landed in yamcs/yamcs commit ecf34a4e2ccb — awaiting tagged release
https://github.com/yamcs/yamcs/commit/ecf34a4e2ccbe085e6ceff0253595b24d5ecb4aagithub_commit
commit 8e18e279d8ce (yamcs/yamcs)
Fix landed in yamcs/yamcs commit 8e18e279d8ce — awaiting tagged release
https://github.com/yamcs/yamcs/commit/8e18e279d8ce761c21f4f67bbd06a1bff804d297Vendor 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.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 5× in last 7d / 5× 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.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-28 22:45 UTCEG score recompute
- 2026-08-28 22:09 UTCEG score recompute
- 2026-08-28 20:25 UTCEG score recompute
- 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. 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 80.6% 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). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
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
Explore the affected products and dependency analysis for CVE-2026-55566
Is Your Infrastructure Affected by CVE-2026-55566?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.