How severe is CVE-2019-12966?

CVE-2019-12966 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-12966 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-12966?

CVE-2019-12966 affects Fehelper Project Fehelper. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-12966?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2019-12966 published?

CVE-2019-12966 was published on 2019-06-26 and last updated on 2026-06-17.

CVE-2019-12966

CVE-2019-12966 is a critical-severity vulnerability in Fehelper Project Fehelper with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Fehelper Project Fehelper
Published: 2019-06-26
Last modified: 2026-06-17

Description

FeHelper through 2019-06-19 allows arbitrary code execution during a JSON format operation, as demonstrated by the {"a":(function(){confirm(1)})()} input.

Frequently asked questions

What is CVE-2019-12966?: FeHelper through 2019-06-19 allows arbitrary code execution during a JSON format operation, as demonstrated by the {"a":(function(){confirm(1)})()} input.
How severe is CVE-2019-12966?: CVE-2019-12966 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-12966 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-12966?: CVE-2019-12966 affects Fehelper Project Fehelper. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-12966?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-12966 published?: CVE-2019-12966 was published on 2019-06-26 and last updated on 2026-06-17.

References

https://github.com/zxlie/FeHelper/issues/63

Affected products (1)

cpe:2.3:a:fehelper_project:fehelper:*:*:*:*:*:*:*:*

Other CWE-74 (Improper Neutralization of Special Elements (Injection)) vulnerabilities

CVE-2026-25586 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty…
CVE-2026-25520 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, The return values of functions aren't wrapped.…
CVE-2025-20265 — Critical (CVSS 10.0): A vulnerability in the RADIUS subsystem implementation of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2025-20337 — Critical (CVSS 10.0): A vulnerability in a specific API of Cisco ISE and Cisco ISE-PIC could allow an unauthenticated, remote attacker to…
CVE-2025-20281 — Critical (CVSS 10.0): A vulnerability in a specific API of Cisco ISE and Cisco ISE-PIC could allow an unauthenticated, remote attacker to…
CVE-2024-42472 — Critical (CVSS 10.0): Flatpak is a Linux application sandboxing and distribution framework. Prior to versions 1.14.0 and 1.15.10, a malicious…

Browse all CWE-74 (Improper Neutralization of Special Elements (Injection)) vulnerabilities →