{"id":"CVE-2019-17026","published":"2020-03-02T05:15:12Z","modified":"2026-06-17T02:23:11Z","title":"Mozilla Firefox And Thunderbird Type Confusion Vulnerability","vendor":"Mozilla","product":"Firefox and Thunderbird","tier":"core","eol":null,"description":{"text":"Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.","provenance":"source","from":"NVD"},"summary":{"text":"Mozilla Firefox and Thunderbird contain a type confusion flaw in the IonMonkey JIT compiler, caused by incorrect alias information when setting array elements. An attacker can exploit it over the network without authentication, but a user must interact with the attacker's content, such as by visiting a malicious page, for the flaw to be triggered.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-31T04:54:18Z"},"cvss":{"score":8.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.46311,"percentile":0.98816,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2019-17026","provenance":"source"},"vulncheckKev":{"dateAdded":"2020-01-07","exploitedFirstSeen":"2020-01-07","ransomware":false,"evidence":[{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2020-01-07"},{"url":"https://blogs.360.cn/post/apt-c-06_0day.html","date":"2020-02-11"},{"url":"https://www.tenable.com/blog/daisy-chaining-how-vulnerabilities-can-be-greater-than-the-sum-of-their-parts","date":"2021-01-21"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"}],"evidenceTotal":4,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-843","name":"Access of Resource Using Incompatible Type"}],"references":[{"url":"http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html","tags":["Exploit","Third Party Advisory","VDB Entry"]},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1607443","tags":["Issue Tracking"]},{"url":"https://security.gentoo.org/glsa/202003-02","tags":["Third Party Advisory"]},{"url":"https://usn.ubuntu.com/4335-1/","tags":["Third Party Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2020-03/","tags":["Vendor Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2020-04/","tags":["Vendor Advisory"]},{"url":"http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html","tags":["Exploit","Third Party Advisory","VDB Entry"]},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1607443","tags":["Issue Tracking"]},{"url":"https://security.gentoo.org/glsa/202003-02","tags":["Third Party Advisory"]},{"url":"https://usn.ubuntu.com/4335-1/","tags":["Third Party Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2020-03/","tags":["Vendor Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2020-04/","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-17026","tags":["US Government Resource"]}],"techniques":[{"id":"T1189","name":"Drive-by Compromise","tactics":["initial-access"],"provenance":"source","basis":"ctid-cve","bases":["ctid-cve","ai-mapping"],"basisDetail":"CTID attack_to_cve (Phase 1); claude-haiku-5-5: drive-by via malicious web content in browser","mappingType":"uncategorized","evidence":[{"from":"description","quote":"We are aware of targeted attacks in the wild abusing this flaw","start":113,"end":175}],"confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1203","name":"Exploitation for Client Execution","tactics":["execution"],"provenance":"source","basis":"ctid-cve","bases":["ctid-cve","ai-mapping"],"basisDetail":"CTID attack_to_cve (Phase 1); claude-haiku-5-5: type confusion triggers client-side exploitation","mappingType":"uncategorized","evidence":[{"from":"description","quote":"Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion","start":0,"end":111}],"confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: JIT type confusion enables arbitrary code execution","mappingType":"primary_impact","evidence":[{"from":"description","quote":"Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion","start":0,"end":111}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2019-7500","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2019-7500","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[{"id":49864,"url":"https://www.exploit-db.com/exploits/49864","title":"Firefox 72 IonMonkey - JIT Type Confusion","type":"local","platform":"windows_x86-64","date":"2021-05-13","verified":false,"provenance":"source"}],"exploitSources":{"exploitdb":{"count":1,"earliest":"2021-05-13"},"pocGithub":{"count":2,"skipped":0,"earliest":"2020-08-27","earliestUrl":"https://github.com/maxpl0it/CVE-2019-17026-Exploit","repos":[{"name":"maxpl0it/CVE-2019-17026-Exploit","url":"https://github.com/maxpl0it/CVE-2019-17026-Exploit","stars":47,"created":"2020-08-27"},{"name":"lsw29475/CVE-2019-17026","url":"https://github.com/lsw29475/CVE-2019-17026","stars":3,"created":"2021-02-24"}]},"first":{"date":"2020-08-27","source":"PoC-in-GitHub","url":"https://github.com/maxpl0it/CVE-2019-17026-Exploit"},"provenance":"source"},"exploitRefs":["http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html"],"flow":[{"stage":"primary","techniques":["T1059"],"provenance":"ai"},{"stage":"related","techniques":["T1189","T1203"],"provenance":"source"}],"timeline":[{"date":"2020-01-07","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","provenance":"source"},{"date":"2020-03-02","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2019-17026","provenance":"source"},{"date":"2020-08-27","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub; 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1 Exploit-DB entry; 2 PoC-in-GitHub repos"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":6.16,"detail":"base score 8.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}