CVE-2026-55637

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (16th percentile of EPSS-scored CVEs). 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
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

genieacs-mcp is an MCP server for GenieACS written in Go. Prior to 0.3.2, the Streamable HTTP transport in cmd/server/main.go creates an unauthenticated /mcp listener on the default MCP_LISTEN_ADDR value 127.0.0.1:8080 when MCP_AUTH_TOKEN is unset and the httpSrv.Start(addr) branch does not validate the Host or Origin headers. A malicious website can use DNS rebinding to send browser requests with attacker-controlled Host and Origin values to the loopback listener, initialize an MCP session, list tools, and invoke operations against the GenieACS NBI configured by ACS_URL. Successful exploitation can expose or modify CPE management state, including device reboots, firmware tasks, TR-069 parameter changes, presets, provisions, tags, connection requests, and task operations. The npm wrapper is not affected because it forces TRANSPORT=stdio and does not expose an HTTP listener. This issue is fixed in version 0.3.2.

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
44
EG Risk 44/100CISA SSVC

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
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
16th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 25, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_release, github, github_commit.
githubMentions a patch (unverified)🟡 PoC Available

DNS rebinding reaches local GenieACS MCP Streamable HTTP transport · Advisory · GeiserX/genieacs-mcp · GitHub

https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wx
github_release Patch Available

v0.3.2

Patch available: GeiserX/genieacs-mcp v0.3.2

https://github.com/GeiserX/genieacs-mcp/releases/tag/v0.3.2
github_pr Patch Available

fix(security): block DNS rebinding on HTTP transport (GHSA-cmwv-wf9p-p8wx)

Patch available: GeiserX/genieacs-mcp v0.3.2 (PR #26 merged 2026-06-14)

https://github.com/GeiserX/genieacs-mcp/pull/26
github_commit Patch Available

commit 577306d78190 (GeiserX/genieacs-mcp)

Patch available: GeiserX/genieacs-mcp v0.3.2 (contains commit 577306d78190)

https://github.com/GeiserX/genieacs-mcp/commit/577306d78190622eee97e362b042a69499ef373f

Vendor Advisories for CVE-2026-55637(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)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/geiserx/genieacs-mcp—
  • every version up to 0.3.2: fixed in 0.3.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 53× 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. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-10 11:46 UTCEG score recompute
  3. 2026-10-09 20:07 UTCEPSS rescore
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  11. 2026-10-05 17:43 UTCEPSS rescore
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  16. 2026-10-03 01:45 UTCEG score recompute
  17. 2026-10-02 17:56 UTCEPSS rescore
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  20. 2026-09-30 20:14 UTCEG score recompute
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  22. 2026-09-30 06:42 UTCEG score recompute
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  24. 2026-09-29 01:35 UTCEG score recompute
  25. 2026-09-28 13:51 UTCEPSS rescore
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  1. 2026-09-27 23:50 UTCEG score recompute
  2. 2026-09-27 13:48 UTCEPSS rescore
  3. 2026-09-26 22:00 UTCEG score recompute
  4. 2026-09-26 15:59 UTCEPSS rescore
  5. 2026-09-25 00:22 UTCEG score recompute
  6. 2026-09-24 14:04 UTCEPSS rescore
  7. 2026-09-23 22:11 UTCEG score recompute
  8. 2026-09-23 17:54 UTCEPSS rescore
  9. 2026-09-22 07:34 UTCEG score recompute
  10. 2026-09-21 05:48 UTCEG score recompute
  11. 2026-09-20 20:16 UTCEPSS rescore
  12. 2026-09-20 04:03 UTCEG score recompute
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  14. 2026-09-18 19:28 UTCEPSS rescore
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  17. 2026-09-16 22:40 UTCEG score recompute
  18. 2026-09-16 14:08 UTCEPSS rescore
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  20. 2026-09-16 05:15 UTCEPSS rescore
  21. 2026-09-15 06:08 UTCEG score recompute
  22. 2026-09-15 03:11 UTCEPSS rescore
  23. 2026-09-14 04:23 UTCEG score recompute
  24. 2026-09-13 16:47 UTCEPSS rescore
  25. 2026-09-13 02:38 UTCEG score recompute
  26. 2026-09-12 00:53 UTCEG score recompute
  27. 2026-09-11 14:53 UTCEPSS rescore
  28. 2026-09-11 12:00 UTCEG score recompute
  29. 2026-09-10 10:07 UTCEG score recompute
  30. 2026-09-10 09:35 UTCEPSS rescore
  31. 2026-09-09 01:12 UTCEG score recompute
  32. 2026-09-08 22:01 UTCEPSS rescore
  33. 2026-09-07 18:21 UTCEG score recompute
  34. 2026-09-07 16:01 UTCEPSS rescore
  35. 2026-09-06 16:22 UTCEG score recompute
  36. 2026-09-06 13:47 UTCEPSS rescore
  37. 2026-09-06 03:29 UTCEG score recompute
  38. 2026-09-05 01:43 UTCEG score recompute
  39. 2026-09-04 12:51 UTCEG score recompute
  40. 2026-09-04 05:06 UTCEPSS rescore
  41. 2026-09-02 21:41 UTCEG score recompute
  42. 2026-09-02 14:12 UTCEPSS rescore
  43. 2026-09-01 19:48 UTCEG score recompute
  44. 2026-09-01 13:54 UTCEPSS rescore
  45. 2026-09-01 06:30 UTCEG score recompute
  46. 2026-09-01 04:40 UTCEPSS rescore
  47. 2026-08-31 04:14 UTCEG score recompute
  48. 2026-08-30 19:17 UTCEPSS rescore
  49. 2026-08-30 02:29 UTCEG score recompute
  50. 2026-08-30 01:22 UTCEPSS rescore
  51. 2026-08-29 00:43 UTCEG score recompute
  52. 2026-08-28 21:41 UTCEPSS rescore
  53. 2026-08-27 22:52 UTCEG score recompute
  54. 2026-08-27 14:25 UTCEPSS rescore
  55. 2026-08-26 21:07 UTCEG score recompute
  56. 2026-08-26 14:46 UTCEPSS rescore
  57. 2026-08-25 19:20 UTCEG score recompute
  58. 2026-08-25 18:19 UTCEG score recompute
  59. 2026-08-25 18:19 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55637?
CVE-2026-55637 is a high vulnerability published on August 25, 2026. genieacs-mcp is an MCP server for GenieACS written in Go. Prior to 0.3.2, the Streamable HTTP transport in cmd/server/main.go creates an unauthenticated /mcp listener on the default MCPLISTENADDR value 127.0.0.1:8080 when MCPAUTHTOKEN is unset and the httpSrv.Start(addr) branch does not validate…
When was CVE-2026-55637 disclosed?
CVE-2026-55637 was first published on August 25, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55637 actively exploited?
CVE-2026-55637 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (16th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55637?
CVE-2026-55637 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55637?
A fix for CVE-2026-55637 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55637 are linked in the Vendor Advisories panel on this page.

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