CVE-2026-42506 (GCVE-0-2026-42506)

Vulnerability from cvelistv5 – Published: 2026-05-22 15:01 – Updated: 2026-05-22 17:45
VLAI
Title
Invoking incorrect handling of namespaced elements in foreign content in golang.org/x/net/html
Summary
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.
Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-22 17:45 UTC
CWE
  • CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Assigner
Go CNA under the Google root
CNA scorecard E 42/100 over 75 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
golang.org/x/net golang.org/x/net/html Affected: 0 , < 0.55.0 (semver)
guessed Create a notification for this product.
Credits
ensy
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.1,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "CHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-42506",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-22T17:45:29.886387Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-22T17:45:49.989Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "golang.org/x/net/html",
          "product": "golang.org/x/net/html",
          "programRoutines": [
            {
              "name": "parser.parse"
            },
            {
              "name": "Parse"
            },
            {
              "name": "ParseFragment"
            },
            {
              "name": "ParseFragmentWithOptions"
            },
            {
              "name": "ParseWithOptions"
            }
          ],
          "vendor": "golang.org/x/net",
          "versions": [
            {
              "lessThan": "0.55.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "ensy"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-22T15:01:21.056Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/issue/79571"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/iI-mYSI0lu8"
        },
        {
          "url": "https://go.dev/cl/781700"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-5025"
        }
      ],
      "title": "Invoking  incorrect handling of namespaced elements in foreign content in golang.org/x/net/html"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-42506",
    "datePublished": "2026-05-22T15:01:21.056Z",
    "dateReserved": "2026-04-28T00:21:12.792Z",
    "dateUpdated": "2026-05-22T17:45:49.989Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-42506",
      "date": "2026-10-11",
      "epss": "0.00333",
      "percentile": "0.24557"
    },
    "microsoft_vex": {
      "current_release_date": "2026-06-28T14:18:05.000Z",
      "cve": "CVE-2026-42506",
      "id": "msrc_CVE-2026-42506",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "product_status:fixed": "26",
      "product_status:known_affected": "26",
      "product_status:known_not_affected": "2",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "Invoking  incorrect handling of namespaced elements in foreign content in golang.org/x/net/html",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-42506.json",
      "version": "12"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "collectionURL": "https://pkg.go.dev",
                "defaultStatus": "unaffected",
                "packageName": "golang.org/x/net/html",
                "product": "golang.org/x/net/html",
                "programRoutines": [
                  {
                    "name": "parser.parse"
                  },
                  {
                    "name": "Parse"
                  },
                  {
                    "name": "ParseFragment"
                  },
                  {
                    "name": "ParseFragmentWithOptions"
                  },
                  {
                    "name": "ParseWithOptions"
                  }
                ],
                "vendor": "golang.org/x/net",
                "versions": [
                  {
                    "lessThan": "0.55.0",
                    "status": "affected",
                    "version": "0",
                    "versionType": "semver"
                  }
                ]
              }
            ],
            "source": "security@golang.org"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:golang:net:*:*:*:*:*:go:*:*",
                    "matchCriteriaId": "38C86E7B-A1CA-4670-B113-FC9585261F6F",
                    "versionEndExcluding": "0.55.0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering."
          },
          {
            "lang": "es",
            "value": "Parsear HTML arbitrario que luego es renderizado usando Render puede resultar en un \u00e1rbol HTML inesperado. Esto puede ser aprovechado para ejecutar ataques XSS en aplicaciones que intentan sanear el HTML de entrada antes de renderizar."
          }
        ],
        "id": "CVE-2026-42506",
        "lastModified": "2026-07-23T16:10:00.137",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 6.1,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "LOW",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "CHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 2.7,
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-42506",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-22T17:45:29.886387Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-05-22T16:16:20.803",
        "references": [
          {
            "source": "security@golang.org",
            "tags": [
              "Issue Tracking"
            ],
            "url": "https://go.dev/cl/781700"
          },
          {
            "source": "security@golang.org",
            "tags": [
              "Issue Tracking"
            ],
            "url": "https://go.dev/issue/79571"
          },
          {
            "source": "security@golang.org",
            "tags": [
              "Mailing List"
            ],
            "url": "https://groups.google.com/g/golang-announce/c/iI-mYSI0lu8"
          },
          {
            "source": "security@golang.org",
            "tags": [
              "Vendor Advisory"
            ],
            "url": "https://pkg.go.dev/vuln/GO-2026-5025"
          }
        ],
        "sourceIdentifier": "security@golang.org",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-79"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-09T04:04:27+00:00",
      "cve": "CVE-2026-42506",
      "id": "CVE-2026-42506",
      "initial_release_date": "2026-05-22T15:01:21.056000+00:00",
      "product_status:fixed": "152",
      "product_status:known_affected": "615",
      "product_status:known_not_affected": "293",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "golang.org/x/net/html: golang.org/x/net/html: Cross-Site Scripting (XSS) via arbitrary HTML parsing",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42506.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "cvssV3_1": {
                  "attackComplexity": "LOW",
                  "attackVector": "NETWORK",
                  "availabilityImpact": "NONE",
                  "baseScore": 6.1,
                  "baseSeverity": "MEDIUM",
                  "confidentialityImpact": "LOW",
                  "integrityImpact": "LOW",
                  "privilegesRequired": "NONE",
                  "scope": "CHANGED",
                  "userInteraction": "REQUIRED",
                  "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
                  "version": "3.1"
                }
              },
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-42506",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-05-22T17:45:29.886387Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-05-22T17:45:46.046Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "collectionURL": "https://pkg.go.dev",
              "defaultStatus": "unaffected",
              "packageName": "golang.org/x/net/html",
              "product": "golang.org/x/net/html",
              "programRoutines": [
                {
                  "name": "parser.parse"
                },
                {
                  "name": "Parse"
                },
                {
                  "name": "ParseFragment"
                },
                {
                  "name": "ParseFragmentWithOptions"
                },
                {
                  "name": "ParseWithOptions"
                }
              ],
              "vendor": "golang.org/x/net",
              "versions": [
                {
                  "lessThan": "0.55.0",
                  "status": "affected",
                  "version": "0",
                  "versionType": "semver"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "value": "ensy"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering."
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
                  "lang": "en"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-22T15:01:21.056Z",
            "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
            "shortName": "Go"
          },
          "references": [
            {
              "url": "https://go.dev/issue/79571"
            },
            {
              "url": "https://groups.google.com/g/golang-announce/c/iI-mYSI0lu8"
            },
            {
              "url": "https://go.dev/cl/781700"
            },
            {
              "url": "https://pkg.go.dev/vuln/GO-2026-5025"
            }
          ],
          "title": "Invoking  incorrect handling of namespaced elements in foreign content in golang.org/x/net/html"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "assignerShortName": "Go",
        "cveId": "CVE-2026-42506",
        "datePublished": "2026-05-22T15:01:21.056Z",
        "dateReserved": "2026-04-28T00:21:12.792Z",
        "dateUpdated": "2026-05-22T17:45:49.989Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.