{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2025-34091", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2025-04-15T19:15:22.551Z", "datePublished": "2025-07-02T19:25:27.579Z", "dateUpdated": "2025-07-03T03:55:40.094Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unknown", "modules": ["Google Chrome Elevation Service (COM registration logic)"], "platforms": ["Windows"], "product": "Chrome", "vendor": "Google", "versions": [{"lessThan": "129", "status": "affected", "version": "127", "versionType": "semver"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Ari Novick of CyberArk Labs"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p></p><p></p><p>A padding oracle vulnerability exists in Google Chrome\u2019s AppBound cookie encryption mechanism due to observable decryption failure behavior in Windows Event Logs when handling malformed ciphertext in SYSTEM-DPAPI-encrypted blobs. A local attacker can repeatedly send malformed ciphertexts to the Chrome elevation service and distinguish between padding and MAC errors, enabling a padding oracle attack. This allows partial decryption of the SYSTEM-DPAPI layer and eventual recovery of the user-DPAPI encrypted cookie key, which is trivially decrypted by the attacker\u2019s own context. This issue undermines the core purpose of AppBound Encryption by enabling low-privileged cookie theft through cryptographic misuse and verbose error feedback.</p><p>Confirmed in Google Chrome with AppBound Encryption enabled. Other Chromium-based browsers may be affected if they implement similar COM-based encryption mechanisms.</p><p>This behavior arises from a combination of Chrome\u2019s AppBound implementation and the way Microsoft Windows DPAPI reports decryption failures via Event Logs. 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Other Chromium-based browsers may be affected if they implement similar COM-based encryption mechanisms.\n\nThis behavior arises from a combination of Chrome\u2019s AppBound implementation and the way Microsoft Windows DPAPI reports decryption failures via Event Logs. 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As such, the vulnerability relies on cryptographic behavior and error visibility in all supported versions of Windows.", "supportingMedia": [{"type": "text/html", "value": "<p></p><p></p><p>A padding oracle vulnerability exists in Google Chrome\u2019s AppBound cookie encryption mechanism due to observable decryption failure behavior in Windows Event Logs when handling malformed ciphertext in SYSTEM-DPAPI-encrypted blobs. A local attacker can repeatedly send malformed ciphertexts to the Chrome elevation service and distinguish between padding and MAC errors, enabling a padding oracle attack. This allows partial decryption of the SYSTEM-DPAPI layer and eventual recovery of the user-DPAPI encrypted cookie key, which is trivially decrypted by the attacker\u2019s own context. This issue undermines the core purpose of AppBound Encryption by enabling low-privileged cookie theft through cryptographic misuse and verbose error feedback.</p><p>Confirmed in Google Chrome with AppBound Encryption enabled. Other Chromium-based browsers may be affected if they implement similar COM-based encryption mechanisms.</p><p>This behavior arises from a combination of Chrome\u2019s AppBound implementation and the way Microsoft Windows DPAPI reports decryption failures via Event Logs. 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