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: 0.2%, top 90% 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
Trending — 3 sources updated this week
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%CVSS: 8.8Exploit: None knownExposed: 0

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

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
8.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 25, 2026

Advisory Details (4)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_release, github, github_commit.
github Patch Available🟡 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.

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.

  1. 2026-08-26 21:07 UTCEG score recompute
  2. 2026-08-26 14:46 UTCEPSS rescore
  3. 2026-08-25 19:20 UTCEG score recompute
  4. 2026-08-25 18:19 UTCEG score recompute
  5. 2026-08-25 18:19 UTCMITRE cvelistV5first tracked

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 in the National Vulnerability Database on August 25, 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% probability of exploitation in the next 30 days, which ranks it in the top 89.6% of all scored CVEs.
What is the CVSS score of CVE-2026-55637?
CVE-2026-55637 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-55637?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55637, 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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