Uncontrolled Recursion in Loofah
## Summary
Loofah `>= 2.2.0, < 2.19.1` uses recursion for sanitizing `CDATA` sections, making it susceptible to stack exhaustion and raising a `SystemStackError` exception. This may lead to a denial of service through CPU resource consumption.
## Mitigation
Upgrade to Loofah `>= 2.19.1`.
Users who are unable to upgrade may be able to mitigate this vulnerability by limiting the length of the strings that are sanitized.
## Severity
The Loofah maintainers have evaluated this as High Severity 7.5 (CVSS3.1)
https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
## References
- CWE - CWE-674: Uncontrolled Recursion (4.9)
https://cwe.mitre.org/data/definitions/674.html