Vulnerability Description
Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape html special characters if the extended grapheme clusters match, which allows bypassing escaping by using an extended grapheme cluster containing both the special html character and some additional characters. In the case of html attributes, this can lead to XSS if there is a leaf variable in the attribute that is user controlled. This vulnerability is fixed in 1.4.1.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Vapor | Leafkit | < 1.14.1 |
Related Weaknesses (CWE)
References
- https://github.com/vapor/leaf-kit/commit/8919e39476c3a4ba05c28b71546bb9195f87ef3Patch
- https://github.com/vapor/leaf-kit/security/advisories/GHSA-4hfh-fch3-5q7pExploitVendor Advisory
FAQ
What is CVE-2026-27120?
CVE-2026-27120 is a vulnerability with a CVSS score of 6.1 (MEDIUM). Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape html special characters if the extended grapheme clusters match, which allows bypa...
How severe is CVE-2026-27120?
CVE-2026-27120 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-27120?
Check the references section above for vendor advisories and patch information. Affected products include: Vapor Leafkit.