CVE-2026-55566

MEDIUMPre-NVD 4.34.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (30th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
4.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 4.3Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
4.3MEDIUMmedium confidence
EG Risk
35
EG Risk 35/100

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 (value × EchelonGraph’s weight)
Severity43% × 45%
The EG Score, 4.3 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
30th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

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 advisoryMentions a patch (unverified)

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 rangeFix by version rangeDependents
org.yamcs:yamcs-core0.29.3 ... 5.9.9 (166 versions)
  • 5.13.0 up to 5.13.2: fixed in 5.13.2
  • every version up to 5.12.8: fixed in 5.12.8
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 53× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:39 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:17 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  9. 2026-10-10 00:53 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  11. 2026-10-09 02:38 UTCEG score recompute
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  13. 2026-10-08 00:51 UTCEG score recompute
  14. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  15. 2026-10-06 23:00 UTCEG score recompute
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  17. 2026-10-06 00:48 UTCEG score recompute
  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  19. 2026-10-05 01:20 UTCEG score recompute
  20. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  21. 2026-10-04 02:43 UTCEG score recompute
  22. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  23. 2026-10-03 04:29 UTCEG score recompute
  24. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  25. 2026-10-02 06:16 UTCEG score recompute
Show 58 more
  1. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  2. 2026-10-01 07:49 UTCEG score recompute
  3. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  4. 2026-09-30 09:36 UTCEG score recompute
  5. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  6. 2026-09-29 11:10 UTCEG score recompute
  7. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  8. 2026-09-27 14:23 UTCEG score recompute
  9. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  10. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  11. 2026-09-26 15:34 UTCEG score recompute
  12. 2026-09-24 15:23 UTCEG score recompute
  13. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  14. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-09-22 18:43 UTCEG score recompute
  16. 2026-09-20 22:05 UTCEG score recompute
  17. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  18. 2026-09-19 23:51 UTCEG score recompute
  19. 2026-09-19 01:38 UTCEG score recompute
  20. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  21. 2026-09-18 03:25 UTCEG score recompute
  22. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  23. 2026-09-17 05:12 UTCEG score recompute
  24. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  25. 2026-09-16 06:58 UTCEG score recompute
  26. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  27. 2026-09-15 08:45 UTCEG score recompute
  28. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  29. 2026-09-14 10:29 UTCEG score recompute
  30. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  31. 2026-09-13 12:16 UTCEG score recompute
  32. 2026-09-11 15:50 UTCEG score recompute
  33. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  34. 2026-09-10 17:37 UTCEG score recompute
  35. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  36. 2026-09-09 19:24 UTCEG score recompute
  37. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  38. 2026-09-08 03:54 UTCEG score recompute
  39. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  40. 2026-09-07 05:41 UTCEG score recompute
  41. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  42. 2026-09-06 07:27 UTCEG score recompute
  43. 2026-09-05 09:12 UTCEG score recompute
  44. 2026-09-04 10:59 UTCEG score recompute
  45. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  46. 2026-09-02 14:24 UTCEG score recompute
  47. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  48. 2026-09-01 16:07 UTCEG score recompute
  49. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  50. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  51. 2026-08-31 17:29 UTCEG score recompute
  52. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  53. 2026-08-30 19:13 UTCEG score recompute
  54. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  55. 2026-08-28 22:45 UTCEG score recompute
  56. 2026-08-28 22:09 UTCEG score recompute
  57. 2026-08-28 20:25 UTCEG score recompute
  58. 2026-08-28 18:10 UTCEG score recomputeFirst assessed: 4.3 MEDIUM

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Frequently asked(5)

What is CVE-2026-55566?
CVE-2026-55566 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-55566 published?
The CVE record for CVE-2026-55566 was published on August 28, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 8, 2026; the record at its source may have been updated since.
Is CVE-2026-55566 actively exploited?
CVE-2026-55566 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (30th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55566?
CVE-2026-55566 has a CVSS base score of 4.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55566?
A fix for CVE-2026-55566 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55566 are linked in the Vendor Advisories panel on this page.

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