CVE-2026-103923 (GCVE-0-2026-103923)

Vulnerability from cvelistv5 – Published: 2026-10-01 17:37 – Updated: 2026-10-01 17:37
VLAI
Title
KaTeX: Existing prototype pollution can bypass trust restrictions
Summary
KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. From 0.11.0 until 0.18.2, KaTeX uses ordinary JavaScript property access for the renderer options object, the trust setting, default and processor setting metadata, and namespace lookup and group restoration, allowing inherited properties to be treated as explicitly supplied values. When Object.prototype is already polluted or an attacker controls the options object's prototype, attacker-controlled mathematical expressions can use an inherited trust value to enable trusted rendering and produce links capable of user-interaction cross-site scripting or loading attacker-selected external resources in a consuming application that inserts unsanitized KaTeX output into a page. KaTeX does not itself create the prototype pollution, and rendering an expression alone does not execute script. This issue is fixed in version 0.18.2.
Severity
2.1 (Low)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CWE
  • CWE-807 - Reliance on Untrusted Inputs in a Security Decision
Assigner
References
Impacted products
Vendor Product Version CPE status
KaTeX KaTeX Affected: >= 0.11.0, < 0.18.2
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "KaTeX",
          "vendor": "KaTeX",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.11.0, \u003c 0.18.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. From 0.11.0 until 0.18.2, KaTeX uses ordinary JavaScript property access for the renderer options object, the trust setting, default and processor setting metadata, and namespace lookup and group restoration, allowing inherited properties to be treated as explicitly supplied values. When Object.prototype is already polluted or an attacker controls the options object\u0027s prototype, attacker-controlled mathematical expressions can use an inherited trust value to enable trusted rendering and produce links capable of user-interaction cross-site scripting or loading attacker-selected external resources in a consuming application that inserts unsanitized KaTeX output into a page. KaTeX does not itself create the prototype pollution, and rendering an expression alone does not execute script. This issue is fixed in version 0.18.2."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.1,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "LOW",
            "userInteraction": "ACTIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-807",
              "description": "CWE-807: Reliance on Untrusted Inputs in a Security Decision",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-01T17:37:47.953Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/KaTeX/KaTeX/security/advisories/GHSA-238p-pmpm-9mq7",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/KaTeX/KaTeX/security/advisories/GHSA-238p-pmpm-9mq7"
        },
        {
          "name": "https://github.com/KaTeX/KaTeX/pull/4260",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/KaTeX/KaTeX/pull/4260"
        },
        {
          "name": "https://github.com/KaTeX/KaTeX/commit/0adf7e77db6915d991803b29699f82b1ccf8d4f4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/KaTeX/KaTeX/commit/0adf7e77db6915d991803b29699f82b1ccf8d4f4"
        },
        {
          "name": "https://github.com/KaTeX/KaTeX/releases/tag/v0.18.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/KaTeX/KaTeX/releases/tag/v0.18.2"
        }
      ],
      "source": {
        "advisory": "GHSA-238p-pmpm-9mq7",
        "discovery": "UNKNOWN"
      },
      "title": "KaTeX: Existing prototype pollution can bypass trust restrictions"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-103923",
    "datePublished": "2026-10-01T17:37:47.953Z",
    "dateReserved": "2026-10-01T14:20:19.154Z",
    "dateUpdated": "2026-10-01T17:37:47.953Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "KaTeX",
                "vendor": "KaTeX",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 0.11.0, \u003c 0.18.2"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. From 0.11.0 until 0.18.2, KaTeX uses ordinary JavaScript property access for the renderer options object, the trust setting, default and processor setting metadata, and namespace lookup and group restoration, allowing inherited properties to be treated as explicitly supplied values. When Object.prototype is already polluted or an attacker controls the options object\u0027s prototype, attacker-controlled mathematical expressions can use an inherited trust value to enable trusted rendering and produce links capable of user-interaction cross-site scripting or loading attacker-selected external resources in a consuming application that inserts unsanitized KaTeX output into a page. KaTeX does not itself create the prototype pollution, and rendering an expression alone does not execute script. This issue is fixed in version 0.18.2."
          }
        ],
        "id": "CVE-2026-103923",
        "lastModified": "2026-10-01T18:17:13.053",
        "metrics": {
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 2.1,
                "baseSeverity": "LOW",
                "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": "LOW",
                "subIntegrityImpact": "LOW",
                "userInteraction": "ACTIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
                "version": "4.0",
                "vulnAvailabilityImpact": "NONE",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "NONE",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-01T18:17:13.053",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/KaTeX/KaTeX/commit/0adf7e77db6915d991803b29699f82b1ccf8d4f4"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/KaTeX/KaTeX/pull/4260"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/KaTeX/KaTeX/releases/tag/v0.18.2"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/KaTeX/KaTeX/security/advisories/GHSA-238p-pmpm-9mq7"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-807"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-02T01:17:34+00:00",
      "cve": "CVE-2026-103923",
      "id": "CVE-2026-103923",
      "initial_release_date": "2026-10-01T17:37:47.953000+00:00",
      "product_status:known_affected": "3",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "katex: katex: Cross-site scripting via prototype pollution inheritance",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-103923.json",
      "version": "3"
    }
  }
}



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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.

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