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CVE-2026-8355

Status: Awaiting AnalysisMedium (5.4)—
Severity5.4Medium · CVSS 3.1
Exploitation probability0.18 %higher than 7% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found

IBM ContextForge MCP Gateway 0.1.0 through 1.0.5 is vulnerable to a server-side request Forgery (SSRF) that allows authenticated users with gateway creation privileges to perform arbitrary HTTP POST requests to internal network resources and cloud metadata endpoints. The vulnerability occurs during OAuth-enabled gateway registration when the system fails to validate the oauth_config.token_url parameter.

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When registering a gateway with OAuth client credentials authentication, an attacker can supply a malicious token_url pointing to internal services, cloud metadata endpoints (AWS IMDSv1, GCP, Azure), or localhost-bound services. The application immediately performs an HTTP POST request to the attacker-controlled URL with form-encoded credentials in the body. If the response cannot be parsed as a valid OAuth token response, up to 256 characters of the response body are reflected back to the attacker in the HTTP 502 error message. This vulnerability bypasses existing SSRF protections that are applied to the gateway.url field but not to OAuth configuration parameters.

CVSS

Base score
5.4
Version
3.1
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days
0.18 %
Percentile among all scored CVEs
7
Score date
10/20/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

El vector PR:L indica red con privilegios (T1210). El texto describe SSRF que hace POST a red interna y metadatos cloud, y refleja hasta 256 caracteres de respuesta al atacante.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

ATT&CK mitigations that cover these techniques

Filter Network TrafficDisable or Remove Feature or ProgramVulnerability ScanningThreat Intelligence ProgramSSL/TLS InspectionPrivileged Account Management

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

IBM — Contextforge MCP GatewayAI

CWEs

References

Show 1 references

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-8355",
  "cveTags": [],
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          "version": "2.0.3",
          "timestamp": "2026-10-20T14:37:11.981399Z"
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          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "LOW"
        },
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        "exploitabilityScore": 2.8
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  "affected": [
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          "versions": [
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  "published": "2026-10-20T00:19:20.530",
  "references": [
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      "url": "https://www.ibm.com/support/pages/node/7285723",
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    }
  ],
  "lastModified": "2026-10-20T15:17:35.683",
  "sourceIdentifier": "psirt@us.ibm.com"
}