Vulnerability-Lookup

FKIE_CVE-2026-34742

Vulnerability from fkie_nvd - Published: 2026-04-02 19:21 - Updated: 2026-07-24 21:10

Severity

8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
8.0 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N

Summary

The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0.

References

URL	Tags
security-advisories@github.com	https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d	Patch
security-advisories@github.com	https://github.com/modelcontextprotocol/go-sdk/pull/760	Issue Tracking, Patch
security-advisories@github.com	https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0	Release Notes
security-advisories@github.com	https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6	Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:21772
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/security/cve/CVE-2026-34742
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://bugzilla.redhat.com/show_bug.cgi?id=2454608
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34742.json

Impacted products

	Vendor	Product	Version
	lfprojects	mcp_go_sdk	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "go-sdk",
          "vendor": "modelcontextprotocol",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.4.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    },
    {
      "affectedData": [
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          "collectionURL": "https://catalog.redhat.com/software/containers/",
          "cpes": [
            "cpe:/a:redhat:openshift_devspaces:3.28::el9"
          ],
          "defaultStatus": "affected",
          "packageName": "devspaces/udi-rhel9",
          "product": "Red Hat OpenShift Dev Spaces 3.28",
          "vendor": "Red Hat",
          "versions": [
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              "lessThan": "*",
              "status": "unaffected",
              "version": "1779829736",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:migration_toolkit_virtualization:2"
          ],
          "defaultStatus": "affected",
          "packageName": "migration-toolkit-virtualization/mtv-cli-download-rhel9",
          "product": "Migration Toolkit for Virtualization",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
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          ],
          "defaultStatus": "affected",
          "packageName": "mtv-candidate/mtv-api-rhel9",
          "product": "Migration Toolkit for Virtualization",
          "vendor": "Red Hat"
        },
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          "vendor": "Red Hat"
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          "cpes": [
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          "defaultStatus": "affected",
          "packageName": "mtv-candidate/mtv-operator-bundle",
          "product": "Migration Toolkit for Virtualization",
          "vendor": "Red Hat"
        },
        {
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          "cpes": [
            "cpe:/a:redhat:openshift_lightspeed"
          ],
          "defaultStatus": "unaffected",
          "packageName": "openshift-lightspeed/openshift-mcp-server-rhel9",
          "product": "OpenShift Lightspeed",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:serverless:1"
          ],
          "defaultStatus": "affected",
          "packageName": "openshift-serverless-1/kn-client-kn-rhel9",
          "product": "OpenShift Serverless",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:serverless:1"
          ],
          "defaultStatus": "affected",
          "packageName": "openshift-serverless-1/kn-plugin-func-func-util-rhel9",
          "product": "OpenShift Serverless",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "defaultStatus": "unaffected",
          "packageName": "rhoai/odh-mod-arch-gen-ai-rhel9",
          "product": "Red Hat OpenShift AI (RHOAI)",
          "vendor": "Red Hat"
        }
      ],
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    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "92CB3EED-2D8E-4ADC-BD05-2A14C13CA7DA",
              "versionEndExcluding": "1.4.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Go MCP SDK used Go\u0027s standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0."
    },
    {
      "lang": "es",
      "value": "El SDK Go de MCP utilizaba el encoding/json est\u00e1ndar de Go. Antes de la versi\u00f3n 1.4.0, el SDK Go del Protocolo de Contexto del Modelo (MCP) no habilita la protecci\u00f3n contra el rebinding de DNS por defecto para servidores basados en HTTP. Cuando un servidor MCP basado en HTTP se ejecuta en localhost sin autenticaci\u00f3n con StreamableHTTPHandler o SSEHandler, un sitio web malicioso podr\u00eda explotar el rebinding de DNS para eludir las restricciones de la pol\u00edtica de mismo origen y enviar solicitudes al servidor MCP local. Esto podr\u00eda permitir a un atacante invocar herramientas o acceder a recursos expuestos por el servidor MCP en nombre del usuario en esas circunstancias limitadas. Este problema ha sido parcheado en la versi\u00f3n 1.4.0."
    }
  ],
  "id": "CVE-2026-34742",
  "lastModified": "2026-07-24T21:10:00.143",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 8.0,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N",
          "version": "3.1"
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        "exploitabilityScore": 1.6,
        "impactScore": 5.8,
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.6,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
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          "version": "4.0",
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          "timestamp": "2026-04-03T15:58:40.335119Z",
          "version": "2.0.3"
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  "published": "2026-04-02T19:21:33.023",
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      "source": "security-advisories@github.com",
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    },
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      "tags": [
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    },
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  ],
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  "vulnStatus": "Modified",
  "weaknesses": [
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          "value": "CWE-1188"
        }
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      "source": "security-advisories@github.com",
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}

CVE-2026-34742 (GCVE-0-2026-34742)

Vulnerability from cvelistv5 – Published: 2026-04-02 18:32 – Updated: 2026-07-15 01:04

Title

Model Context Protocol Go SDK: DNS Rebinding Protection Disabled by Default for Servers Running on Localhost

Summary

Severity

7.6 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

8 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-03 15:58 UTC

CWE

CWE-1188 - Insecure Default Initialization of Resource
CWE-1188 - Initialization of a Resource with an Insecure Default

Assigner

GitHub_M mitre root

References

8 references

URL	Tags
https://github.com/modelcontextprotocol/go-sdk/se…	x_refsource_CONFIRM
https://github.com/modelcontextprotocol/go-sdk/pull/760	x_refsource_MISC
https://github.com/modelcontextprotocol/go-sdk/co…	x_refsource_MISC
https://github.com/modelcontextprotocol/go-sdk/re…	x_refsource_MISC
https://access.redhat.com/security/cve/CVE-2026-34742	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2454608	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:21772	vendor-advisoryx_refsource_REDHAT

Impacted products

6 products

Vendor	Product	Version
modelcontextprotocol	go-sdk	Affected: < 1.4.0
Red Hat	Red Hat OpenShift Dev Spaces 3.28	Unaffected: 1779829736 , < * (rpm) cpe:/a:redhat:openshift_devspaces:3.28::el9
Red Hat	Migration Toolkit for Virtualization	cpe:/a:redhat:migration_toolkit_virtualization:2
Red Hat	OpenShift Lightspeed	cpe:/a:redhat:openshift_lightspeed
Red Hat	OpenShift Serverless	cpe:/a:redhat:serverless:1
Red Hat	Red Hat OpenShift AI (RHOAI)	cpe:/a:redhat:openshift_ai

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34742",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-03T15:58:40.335119Z",
                "version": "2.0.3"
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        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-03T15:59:37.091Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
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            "collectionURL": "https://catalog.redhat.com/software/containers/",
            "cpes": [
              "cpe:/a:redhat:openshift_devspaces:3.28::el9"
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            "packageName": "devspaces/udi-rhel9",
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            "product": "Migration Toolkit for Virtualization",
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            "cpes": [
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            "cpes": [
              "cpe:/a:redhat:openshift_ai"
            ],
            "defaultStatus": "unaffected",
            "packageName": "rhoai/odh-mod-arch-gen-ai-rhel9",
            "product": "Red Hat OpenShift AI (RHOAI)",
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        ],
        "metrics": [
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              {
                "cweId": "CWE-1188",
                "description": "Initialization of a Resource with an Insecure Default",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-15T01:04:01.603Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-34742"
          },
          {
            "name": "RHBZ#2454608",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2454608"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34742.json"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:21772"
          }
        ],
        "solutions": [
          {
            "lang": "en",
            "value": "RHSA-2026:21772: Red Hat OpenShift Dev Spaces 3.28"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2026-04-02T19:06:39.830Z",
            "value": "Reported to Red Hat."
          },
          {
            "lang": "en",
            "time": "2026-04-02T18:32:34.781Z",
            "value": "Made public."
          }
        ],
        "title": "github.com/modelcontextprotocol/go-sdk: Model Context Protocol (MCP) Go SDK: DNS rebinding vulnerability allows unauthorized access",
        "workarounds": [
          {
            "lang": "en",
            "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."
          }
        ],
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "go-sdk",
          "vendor": "modelcontextprotocol",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.4.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The Go MCP SDK used Go\u0027s standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 7.6,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1188",
              "description": "CWE-1188: Insecure Default Initialization of Resource",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-02T18:32:34.781Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6"
        },
        {
          "name": "https://github.com/modelcontextprotocol/go-sdk/pull/760",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/go-sdk/pull/760"
        },
        {
          "name": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d"
        },
        {
          "name": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0"
        }
      ],
      "source": {
        "advisory": "GHSA-xw59-hvm2-8pj6",
        "discovery": "UNKNOWN"
      },
      "title": "Model Context Protocol Go SDK: DNS Rebinding Protection Disabled by Default for Servers Running on Localhost"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-34742",
    "datePublished": "2026-04-02T18:32:34.781Z",
    "dateReserved": "2026-03-30T19:17:10.224Z",
    "dateUpdated": "2026-07-15T01:04:01.603Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

FKIE_CVE-2026-34742

CVE-2026-34742 (GCVE-0-2026-34742)

Tags

Sightings

Nomenclature