MediumCVE-2026-53708

    ContextForge: DNS TOCTOU race condition causes SSRF protection bypass (`/admin/gateways/test`) (CVE-2026-53708)

    Published Last modified Sources: CVE.org, OSV, Hersteller

    What is affected, what to do

    ContextForge is an AI gateway, registry, and proxy that provides centralized discovery, guardrails, and management for MCP, A2A, and REST or gRPC APIs. Prior to 1.0.3, the /admin/gateways/test call site in mcpgateway/admin.py calls validate_gateway_test_url() in mcpgateway/common/validators.py to resolve and reject private, loopback, link-local, and cloud-metadata addresses, but ResilientHttpClient later resolves the original hostname again without binding the validated address.

    Update IBM Mcp-context-forge to version 1.0.3, IBM Mcp-contextforge-gateway to version 1.0.3.

    Affected
    • IBM Mcp-context-forge lt *..1.0.3
    • IBM Mcp-contextforge-gateway lt *..1.0.3
    Fixed in
    • IBM Mcp-context-forge 1.0.3
    • IBM Mcp-contextforge-gateway 1.0.3

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    6.6

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    6.6

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: CVE.org, OSV, Hersteller

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 28.7

    Show all metrics
    Severity
    Medium
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    66.19 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    6.6 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.6
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.4 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    28.7
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: proof of concept · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 14 September 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-350, CWE-367, CWE-918

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    ContextForge is an AI gateway, registry, and proxy that provides centralized discovery, guardrails, and management for MCP, A2A, and REST or gRPC APIs. Prior to 1.0.3, the /admin/gateways/test call site in mcpgateway/admin.py calls validate_gateway_test_url() in mcpgateway/common/validators.py to resolve and reject private, loopback, link-local, and cloud-metadata addresses, but ResilientHttpClient later resolves the original hostname again without binding the validated address. When MCPGATEWAY_ADMIN_API_ENABLED is enabled, an attacker with a database-backed role containing explicit gateways.read permission can use DNS rebinding to return a public address during validation and a private or metadata address during connection, bypassing ssrf_blocked_networks and ssrf_dns_fail_closed because those controls apply only to the validation-time result. The endpoint's allow_admin_bypass=False setting means a bootstrap-only virtual platform-admin identity without a database role is not sufficient. Successful exploitation can reach internal services and cloud metadata, expose cloud credentials, access internal APIs, or probe internal network ports. This issue is fixed in version 1.0.3.

    Source: NVD (NIST), cvelistv5, OSV (Open Source Vulnerabilities), GitHub Security Advisories

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    IBMmcp-context-forge
    • < 1.0.3
    • 1.0.3
    IBMmcp-contextforge-gateway
    • < 1.0.3
    • 1.0.3
    pypimcp-contextforge-gateway
    • 0.6.0
    • 0.3.1
    • 1.0.0
    • 0.2.0
    • 0.8.0
    • 1.0.0rc1
    • 0.9.0
    • 0.4.0
    • 0.1.1
    • 0.5.0
    • 1.0.2
    • 0.3.0
    • 0.7.0
    • 0.1.0
    • 1.0.1
    • 1.0.0b1
    • 1.0.0b2
    • —
    • —
    • —
    • —
    • —
    • —
    • —
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    Vendors and products

    Weakness classes (CWE)

    • CWE-350Reliance on Reverse DNS Resolution for a Security-Critical Action

      Variant

      The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.

      Entry at MITRE CWE-350

    • CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition

      Base

      The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

      Entry at MITRE CWE-367

    • CWE-918Server-Side Request Forgery (SSRF)

      Base

      The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

      Entry at MITRE CWE-918

    References & sources

    • github.comIBM/mcp-context-forge/security/advisories/GHSA-9hgc-g3w5-67cmweb, x_refsource_CONFIRM
    • github.comIBM/mcp-context-forgepackage
    • github.comIBM/mcp-context-forge/releases/tag/v1.0.3web, x_refsource_MISC
    • pypi.orgproject/mcp-contextforge-gatewaypackage
    • GitHub Security Advisoriesadvisories/GHSA-9hgc-g3w5-67cmadvisory
    • NVD (NIST)vuln/detail/CVE-2026-53708advisory
    • github.comIBM/mcp-context-forge/commit/fba11a99babd80779fa05510b35fb6a153…x_refsource_MISC

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: proof of concept, automatable: no

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/IBM/mcp-context-forge/security/advisories/GHSA-9hgc-g3w5-67cm
      SSVC assessmentadded
      —
      {"id":"CVE-2026-53708","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-14T16:33:14.079728Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. ReceivedGitHub

      CVSS V3.1: AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:N

      Weakness type: CWE-918, CWE-350, CWE-367

      Description added or changed

      Show 9 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      ContextForge is an AI gateway, registry, and proxy that provides centralized discovery, guardrails, and management for MCP, A2A, and REST or gRPC APIs. Prior to 1.0.3, the /admin/gateways/test call site in mcpgateway/admin.py calls validate_gateway_test_url() in mcpgateway/common/validators.py to resolve and reject private, loopback, link-local, and cloud-metadata addresses, but ResilientHttpClient later resolves the original hostname again without binding the validated address. When MCPGATEWAY_ADMIN_API_ENABLED is enabled, an attacker with a database-backed role containing explicit gateways.read permission can use DNS rebinding to return a public address during validation and a private or metadata address during connection, bypassing ssrf_blocked_networks and ssrf_dns_fail_closed because those controls apply only to the validation-time result. The endpoint's allow_admin_bypass=False setting means a bootstrap-only virtual platform-admin identity without a database role is not sufficient. Successful exploitation can reach internal services and cloud metadata, expose cloud credentials, access internal APIs, or probe internal network ports. This issue is fixed in version 1.0.3.
      CVSSadded
      —
      AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:N
      Weakness type (CWE)added
      —
      CWE-918
      Weakness type (CWE)added
      —
      CWE-350
      Weakness type (CWE)added
      —
      CWE-367
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/53xxx/CVE-2026-53708.json">CVE-2026-53708</a>
      Referenceadded
      —
      https://github.com/IBM/mcp-context-forge/commit/fba11a99babd80779fa05510b35fb6a153bbacaf
      Referenceadded
      —
      https://github.com/IBM/mcp-context-forge/releases/tag/v1.0.3
      Referenceadded
      —
      https://github.com/IBM/mcp-context-forge/security/advisories/GHSA-9hgc-g3w5-67cm

      Source identifier: security-advisories@github.com

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