{"id":"CVE-2025-62494","state":"PUBLISHED","title":"Type confusion in string addition in QuickJS","description":"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.","publishedAt":"2025-10-16T15:51:50.977Z","updatedAt":"2025-10-16T17:46:39.174Z","severity":{"score":7.1,"label":"High","version":"4.0","vector":"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","source":"Google"},"assigner":"Google","products":["QuickJS QuickJS"],"affected":[{"vendor":"QuickJS","product":"QuickJS","packageName":"JS_ConcatStringInPlace","defaultStatus":"unaffected","versions":[{"version":"2025-04-26","status":"affected","lessThan":"2025-09-13","versionType":"date"}],"collectionURL":"https://bellard.org/quickjs/"}],"references":["https://bellard.org/quickjs/Changelog","https://issuetracker.google.com/434193023"],"weaknesses":["CWE-704"],"ingestedAt":"2026-10-29T20:09:48.677Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/62xxx/CVE-2025-62494.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2025-62494","state":"PUBLISHED","datePublished":"2025-10-16T15:51:50.977Z","dateUpdated":"2025-10-16T17:46:39.174Z","assignerShortName":"Google","assignerOrgId":"14ed7db2-1595-443d-9d34-6215bf890778","dateReserved":"2025-10-15T08:47:41.878Z"},"containers":{"cna":{"title":"Type confusion in string addition in QuickJS","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."}],"affected":[{"vendor":"QuickJS","product":"QuickJS","packageName":"JS_ConcatStringInPlace","defaultStatus":"unaffected","versions":[{"version":"2025-04-26","status":"affected","lessThan":"2025-09-13","versionType":"date"}],"collectionURL":"https://bellard.org/quickjs/"}],"references":[{"url":"https://bellard.org/quickjs/Changelog"},{"url":"https://issuetracker.google.com/434193023"}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"HIGH","attackRequirements":"PRESENT","attackVector":"ADJACENT","baseScore":7.1,"baseSeverity":"HIGH","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","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-704","description":"CWE-704 Incorrect Type Conversion or Cast","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"Google","orgId":"14ed7db2-1595-443d-9d34-6215bf890778","dateUpdated":"2025-10-16T15:51:50.977Z"},"credits":[{"lang":"en","type":"finder","value":"Google Big Sleep"}],"datePublic":"2025-07-24T22:00:00.000Z","impacts":[{"capecId":"CAPEC-175","descriptions":[{"lang":"en","value":"CAPEC-175 Code Inclusion"}]}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-10-16T17:46:18.542287Z","id":"CVE-2025-62494","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-16T17:46:39.174Z"}}]}}}