CVE-2019-18848 is a high-severity (CVSS 7.5) Improper Authentication vulnerability in json-jwt. A fix is available for json-jwt — see the affected versions and patch details below.
JSON-jwt Gem lacked element count during splitting of JWE string
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
json-jwtReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
The json-jwt gem before 1.11.0 for Ruby lacks an element count during the splitting of a JWE string.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | json-jwt | all versions | 1.11.0bundle update json-jwt --conservative |
Affected Products
debian linuxdebianjson-jwtjson-jwt_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for json-jwt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update json-jwt to 1.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-18848 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2019-18848 in your dependencies?
Find it across RubyGems, including transitive dependencies.