What is CVE-2026-27120?

CVE-2026-27120 is a medium-severity vulnerability in Vapor Leaf-kit, classified under CWE-75. CVSS score: 6.1/10. Published 2026-02-20.

How severe is CVE-2026-27120?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Vapor Leaf-kit

CVE-2026-27120

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 gra…

EPSS: 0.000 (4.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Vapor Leaf-kit — versions < 1.4.1

Weakness classification (CWE)

References

https://github.com/vapor/leaf-kit/security/advisories/GHSA-4hfh-fch3-5q7p (x_refsource_CONFIRM)
https://github.com/vapor/leaf-kit/commit/8919e39476c3a4ba05c28b71546bb9195f87ef34 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-27120?: CVE-2026-27120 is a medium-severity vulnerability in Vapor Leaf-kit, classified under CWE-75. CVSS score: 6.1/10. Published 2026-02-20.
How severe is CVE-2026-27120?: Medium severity. CVSS v3 base score is 6.1 out of 10.