Vulnerability-Lookup

CVE-2025-62494 (GCVE-0-2025-62494)

Vulnerability from cvelistv5 – Published: 2025-10-16 15:51 – Updated: 2025-10-16 17:46

Title

Type confusion in string addition in QuickJS

Summary

A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine. * The code first checks if the left-hand operand is a string. * It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf). * During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array). * The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string. This mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.

Severity

7.1 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-10-16 17:46 UTC

CWE

CWE-704 - Incorrect Type Conversion or Cast

Assigner

Google CNA under the Google root

CNA scorecard C 75/100 over 33 records in the last 180 days details

References

2 references

URL	Tags
https://bellard.org/quickjs/Changelog
https://issuetracker.google.com/434193023

Impacted products

1 product

Vendor	Product	Version	CPE status
QuickJS	QuickJS	Affected: 2025-04-26 , < 2025-09-13 (date)	guessed

Date Public

2025-07-24 22:00

Credits

Google Big Sleep

Show details on NVD website

JSON

To clipboard

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        "datePublished": "2025-10-16T15:51:50.977Z",
        "dateReserved": "2025-10-15T08:47:41.878Z",
        "dateUpdated": "2025-10-16T17:46:39.174Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}

FKIE_CVE-2025-62494

Vulnerability from fkie_nvd - Published: 2025-10-16 16:15 - Updated: 2026-06-17 09:51

Severity

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

Summary

References

	URL	Tags
	cve-coordination@google.com	https://bellard.org/quickjs/Changelog	Release Notes
	cve-coordination@google.com	https://issuetracker.google.com/434193023	Exploit, Issue Tracking

Impacted products

	Vendor	Product	Version
	quickjs_project	quickjs	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://bellard.org/quickjs/",
          "defaultStatus": "unaffected",
          "packageName": "JS_ConcatStringInPlace",
          "product": "QuickJS",
          "vendor": "QuickJS",
          "versions": [
            {
              "lessThan": "2025-09-13",
              "status": "affected",
              "version": "2025-04-26",
              "versionType": "date"
            }
          ]
        }
      ],
      "source": "cve-coordination@google.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:quickjs_project:quickjs:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "AB84E2DC-74EA-4956-9521-C2B652B8E8C2",
              "versionEndExcluding": "2025-09-13",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.\n\n  *  The code first checks if the left-hand operand is a string.\n\n\n  *  It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).\n\n\n  *  During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).\n\n\n  *  The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.\n\n\nThis mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime."
    }
  ],
  "id": "CVE-2025-62494",
  "lastModified": "2026-06-17T09:51:58.890",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "ADJACENT",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.1,
          "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": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/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": "LOW",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "cve-coordination@google.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-62494",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-10-16T17:46:18.542287Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-10-16T16:15:39.943",
  "references": [
    {
      "source": "cve-coordination@google.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://bellard.org/quickjs/Changelog"
    },
    {
      "source": "cve-coordination@google.com",
      "tags": [
        "Exploit",
        "Issue Tracking"
      ],
      "url": "https://issuetracker.google.com/434193023"
    }
  ],
  "sourceIdentifier": "cve-coordination@google.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-704"
        }
      ],
      "source": "cve-coordination@google.com",
      "type": "Secondary"
    }
  ]
}

GHSA-7GCV-76G2-94QM

Vulnerability from github – Published: 2025-10-16 18:30 – Updated: 2025-10-29 21:30

Details

A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.

The code first checks if the left-hand operand is a string.
It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).
During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).
The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.

This mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.

Severity

8.8 (High)


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

7.1 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2025-62494"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-704"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-10-16T16:15:39Z",
    "severity": "HIGH"
  },
  "details": "A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.\n\n  *  The code first checks if the left-hand operand is a string.\n\n\n  *  It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).\n\n\n  *  During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).\n\n\n  *  The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.\n\n\nThis mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.",
  "id": "GHSA-7gcv-76g2-94qm",
  "modified": "2025-10-29T21:30:32Z",
  "published": "2025-10-16T18:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-62494"
    },
    {
      "type": "WEB",
      "url": "https://bellard.org/quickjs/Changelog"
    },
    {
      "type": "WEB",
      "url": "https://issuetracker.google.com/434193023"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/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",
      "type": "CVSS_V4"
    }
  ]
}

UBUNTU-CVE-2025-62494 (CVE-2025-62494)

Vulnerability from osv_ubuntu – Published: 2025-10-16 16:15 – Updated: 2026-10-17 09:36 – Source website

Details

Severity

7.1 (High)


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

8.8 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2025-62494	REPORT
	https://www.cve.org/CVERecord?id=CVE-2025-62494	REPORT
	https://issuetracker.google.com/434193023	REPORT
	https://bellard.org/quickjs/Changelog	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libquickjs",
            "binary_version": "2021.03.27-1ubuntu0.1~esm1"
          },
          {
            "binary_name": "quickjs",
            "binary_version": "2021.03.27-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "quickjs",
        "purl": "pkg:deb/ubuntu/quickjs@2021.03.27-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2021.03.27-1",
        "2021.03.27-1ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libquickjs",
            "binary_version": "2025.04.26-1"
          },
          {
            "binary_name": "quickjs",
            "binary_version": "2025.04.26-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "quickjs",
        "purl": "pkg:deb/ubuntu/quickjs@2025.04.26-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2024.01.13-5",
        "2025.04.26-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libquickjs",
            "binary_version": "2025.04.26-1build1"
          },
          {
            "binary_name": "quickjs",
            "binary_version": "2025.04.26-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.10",
        "name": "quickjs",
        "purl": "pkg:deb/ubuntu/quickjs@2025.04.26-1build1?arch=source\u0026distro=stonking"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2025.04.26-1build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libquickjs",
            "binary_version": "2025.04.26-1build1"
          },
          {
            "binary_name": "quickjs",
            "binary_version": "2025.04.26-1build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "quickjs",
        "purl": "pkg:deb/ubuntu/quickjs@2025.04.26-1build1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2025.04.26-1",
        "2025.04.26-1build1"
      ]
    }
  ],
  "aliases": [],
  "details": "A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.   *  The code first checks if the left-hand operand is a string.   *  It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).   *  During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).   *  The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string. This mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.",
  "id": "UBUNTU-CVE-2025-62494",
  "modified": "2026-10-17T09:36:23Z",
  "published": "2025-10-16T16:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-62494"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-62494"
    },
    {
      "type": "REPORT",
      "url": "https://issuetracker.google.com/434193023"
    },
    {
      "type": "REPORT",
      "url": "https://bellard.org/quickjs/Changelog"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-62494"
  ]
}

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

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

Action not permitted

CVE-2025-62494 (GCVE-0-2025-62494)

FKIE_CVE-2025-62494

GHSA-7GCV-76G2-94QM

UBUNTU-CVE-2025-62494 (CVE-2025-62494)

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Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour