CVE-2026-56858 (GCVE-0-2026-56858)

Vulnerability from cvelistv5 – Published: 2026-08-13 21:58 – Updated: 2026-08-14 15:32
VLAI
Title
Fix Javascript regexp context tracking in html/template
Summary
Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS.
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 2026-08-14 15:31 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
Go standard library html/template Affected: 0 , < 1.25.13 (semver)
Affected: 1.26.0-0 , < 1.26.6 (semver)
Affected: 1.27.0-0 , < 1.27.0-rc.3 (semver)
guessed Create a notification for this product.
Credits
Ali Sherif
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-2026-56858",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-14T15:31:30.140536Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-79",
                "description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-14T15:32:29.852Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "html/template",
          "product": "html/template",
          "programRoutines": [
            {
              "name": "tJS"
            },
            {
              "name": "Template.Execute"
            },
            {
              "name": "Template.ExecuteTemplate"
            }
          ],
          "vendor": "Go standard library",
          "versions": [
            {
              "lessThan": "1.25.13",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThan": "1.26.6",
              "status": "affected",
              "version": "1.26.0-0",
              "versionType": "semver"
            },
            {
              "lessThan": "1.27.0-rc.3",
              "status": "affected",
              "version": "1.27.0-0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Ali Sherif"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Previously, pathological inputs could close an unescaped \u0027/\u0027 early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-13T21:58:53.354Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/issue/80435"
        },
        {
          "url": "https://go.dev/cl/807100"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/94pEornpRlI"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-6091"
        }
      ],
      "title": "Fix Javascript regexp context tracking in html/template"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-56858",
    "datePublished": "2026-08-13T21:58:53.354Z",
    "dateReserved": "2026-06-23T15:10:49.353Z",
    "dateUpdated": "2026-08-14T15:32:29.852Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-56858",
      "date": "2026-10-15",
      "epss": "0.0031",
      "percentile": "0.22192"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-17T01:54:55.000Z",
      "cve": "CVE-2026-56858",
      "id": "msrc_CVE-2026-56858",
      "initial_release_date": "2026-08-20T22:02:44.000Z",
      "product_status:known_affected": "4",
      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "Fix Javascript regexp context tracking in html/template",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-56858.json",
      "version": "5"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "collectionURL": "https://pkg.go.dev",
                "defaultStatus": "unaffected",
                "packageName": "html/template",
                "product": "html/template",
                "programRoutines": [
                  {
                    "name": "tJS"
                  },
                  {
                    "name": "Template.Execute"
                  },
                  {
                    "name": "Template.ExecuteTemplate"
                  }
                ],
                "vendor": "Go standard library",
                "versions": [
                  {
                    "lessThan": "1.25.13",
                    "status": "affected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "1.26.6",
                    "status": "affected",
                    "version": "1.26.0-0",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "1.27.0-rc.3",
                    "status": "affected",
                    "version": "1.27.0-0",
                    "versionType": "semver"
                  }
                ]
              }
            ],
            "source": "security@golang.org"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Previously, pathological inputs could close an unescaped \u0027/\u0027 early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS."
          }
        ],
        "id": "CVE-2026-56858",
        "lastModified": "2026-09-03T16:37:52.170",
        "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-2026-56858",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-14T15:31:30.140536Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-08-13T22:17:22.207",
        "references": [
          {
            "source": "security@golang.org",
            "url": "https://go.dev/cl/807100"
          },
          {
            "source": "security@golang.org",
            "url": "https://go.dev/issue/80435"
          },
          {
            "source": "security@golang.org",
            "url": "https://groups.google.com/g/golang-announce/c/94pEornpRlI"
          },
          {
            "source": "security@golang.org",
            "url": "https://pkg.go.dev/vuln/GO-2026-6091"
          }
        ],
        "sourceIdentifier": "security@golang.org",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-79"
              }
            ],
            "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-10-15T11:15:30+00:00",
      "cve": "CVE-2026-56858",
      "id": "CVE-2026-56858",
      "initial_release_date": "2026-08-13T21:58:53.354000+00:00",
      "product_status:fixed": "6934",
      "product_status:known_affected": "205",
      "product_status:known_not_affected": "3450",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "html/template: golang: Go html/template: Cross-Site Scripting via pathological input",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56858.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-08T17:11:40Z",
      "cve": "CVE-2026-56858",
      "id": "CVE-2026-56858",
      "initial_release_date": "2026-08-14T23:48:57Z",
      "product_status:known_affected": "24",
      "product_status:known_not_affected": "99",
      "product_status:recommended": "382",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-56858",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-56858.json",
      "version": "11"
    },
    "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-2026-56858",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-08-14T15:31:30.140536Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "problemTypes": [
              {
                "descriptions": [
                  {
                    "cweId": "CWE-79",
                    "description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
                    "lang": "en",
                    "type": "CWE"
                  }
                ]
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-08-14T15:32:20.906Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "collectionURL": "https://pkg.go.dev",
              "defaultStatus": "unaffected",
              "packageName": "html/template",
              "product": "html/template",
              "programRoutines": [
                {
                  "name": "tJS"
                },
                {
                  "name": "Template.Execute"
                },
                {
                  "name": "Template.ExecuteTemplate"
                }
              ],
              "vendor": "Go standard library",
              "versions": [
                {
                  "lessThan": "1.25.13",
                  "status": "affected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThan": "1.26.6",
                  "status": "affected",
                  "version": "1.26.0-0",
                  "versionType": "semver"
                },
                {
                  "lessThan": "1.27.0-rc.3",
                  "status": "affected",
                  "version": "1.27.0-0",
                  "versionType": "semver"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "value": "Ali Sherif"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "Previously, pathological inputs could close an unescaped \u0027/\u0027 early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS."
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
                  "lang": "en"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-13T21:58:53.354Z",
            "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
            "shortName": "Go"
          },
          "references": [
            {
              "url": "https://go.dev/issue/80435"
            },
            {
              "url": "https://go.dev/cl/807100"
            },
            {
              "url": "https://groups.google.com/g/golang-announce/c/94pEornpRlI"
            },
            {
              "url": "https://pkg.go.dev/vuln/GO-2026-6091"
            }
          ],
          "title": "Fix Javascript regexp context tracking in html/template"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "assignerShortName": "Go",
        "cveId": "CVE-2026-56858",
        "datePublished": "2026-08-13T21:58:53.354Z",
        "dateReserved": "2026-06-23T15:10:49.353Z",
        "dateUpdated": "2026-08-14T15:32:29.852Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    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.