PatchTheCVECVE-2019-12966: FeHelper through 2019-06-19 allows arbitrary code execution during a JSON format operation, as demonstrated by
CVE-2019-12966 is a critical-severity flaw (CVSS 9.8) affecting fehelper. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
FeHelper through 2019-06-19 allows arbitrary code execution during a JSON format operation, as demonstrated by the {"a":(function(){confirm(1)})()} input.
Why this priority
- Critical severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 2.4% (top 16%) |
| CISA exploited list | No |
| Weakness | CWE-74 |
| Published | 2019-06-26 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2019-12966?
fehelper: upgrade to newer than 2019-06-19. Exact commands for each OS are on this page.
Is CVE-2019-12966 being exploited?
CVE-2019-12966 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2019-12966 affect?
CVE-2019-12966 affects fehelper. Severity is critical (CVSS 9.8). FeHelper through 2019-06-19 allows arbitrary code execution during a JSON format operation, as demonstrated by the {"a":(function(){confirm(1)})()} input.
How urgent is CVE-2019-12966?
Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action