{"id":"CVE-2018-20840","url":"https://www.cyber-defence.io/tools/cve/CVE-2018-20840","generatedAt":"2026-10-28T21:30:29.674Z","title":"An unhandled exception vulnerability exists during Google Sign-In with Google API C++ Client before 2019-04-10.","description":"An unhandled exception vulnerability exists during Google Sign-In with Google API C++ Client before 2019-04-10. It potentially causes an outage of third-party services that were not designed to recover from exceptions. On the client, ID token handling can cause an unhandled exception because of misinterpretation of an integer as a string, resulting in denial-of-service and then other users can no longer login/sign-in to the affected third-party service. Once this third-party service uses Google Sign-In with google-api-cpp-client, a malicious user can trigger this client/auth/oauth2_authorization.cc vulnerability by requesting the client to receive the ID token from a Google authentication server.","published":"2019-05-30T16:29:01.000Z","lastModified":"2026-06-17T01:53:34.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.0","score":8.6,"severity":"HIGH","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H"},"cwe":["CWE-754"],"affected":["google/api c\\+\\+ client"],"epss":{"score":0.00651,"percentile":0.50995,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.65%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/google/google-api-cpp-client/issues/57","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/google/google-api-cpp-client/pull/58","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/google/google-api-cpp-client/issues/57","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/google/google-api-cpp-client/pull/58","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2018-20840","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}