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 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 v3.1

6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS v3.1

6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

0.23% chance of exploitation in the next 30 days, 14th percentile

Published

2026-02-20

Updated

2026-02-24

Proof-of-concept exploits (1)

• advisories/GHSA-4hfh-fch3-5q7p

References

• CVE Record
• NVD entry

Related

• CVE-2026-27116
• CVE-2026-27124
• CVE-2026-27114
• CVE-2026-27126
• CVE-2026-2711
• CVE-2026-27129