CVE-2019-17026
Actively exploited. CVE-2019-17026 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2019-17026 is indexed in Exploit-DB and GitHub PoC. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
Mozilla Firefox and Thunderbird contain a type confusion vulnerability due to incorrect alias information in the IonMonkey JIT compiler when setting array elements.
CSIRTS triage
- What
- The vulnerability is a type confusion issue in the IonMonkey JIT compiler.
- Who is affected
- Users of Mozilla Firefox and Thunderbird are affected.
- Urgency
- Immediate action is necessary due to the critical nature of the vulnerability.
- Action
- Update to the latest versions of Firefox and Thunderbird.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 99% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2019-17026 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- Exploit-DBA public exploit is published in the Exploit-DB archive.look it up ↗
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2019-17026: Mozilla Firefox And Thunderbird Type Confusion Vulnerabilitycisa-kev · 2021-11-03
External references
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[](https://www.csirts.com/cve/CVE-2019-17026)