CVE-2021-37634
Versions prior to 1.3.0 are susceptible to Cross-site Scripting (XSS) attacks.
Does this matter?
Lower severity and a low EPSS score (0.71%). Track it; it rarely justifies an emergency change on its own.
Description
Leafkit is a templating language with Swift-inspired syntax. Versions prior to 1.3.0 are susceptible to Cross-site Scripting (XSS) attacks. This affects anyone passing unsanitised data to Leaf's variable tags. Before this fix, Leaf would not escape any strings passed to tags as variables. If an attacker managed to find a variable that was rendered with their unsanitised data, they could inject scripts into a generated Leaf page, which could enable XSS attacks if other mitigations such as a Content Security Policy were not enabled. This has been patched in 1.3.0. As a workaround sanitize any untrusted input before passing it to Leaf and enable a CSP to block inline script and CSS data.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 0.71% probability · 52th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- vapor/leafkit
- Source
- security-advisories@github.com
References
- https://github.com/vapor/leaf-kit-ghsa-rv3x-xq3r-8j9h/pull/1Broken Link
- https://github.com/vapor/leaf-kit/security/advisories/GHSA-rv3x-xq3r-8j9hThird Party Advisory
- https://github.com/vapor/leaf-kit-ghsa-rv3x-xq3r-8j9h/pull/1Broken Link
- https://github.com/vapor/leaf-kit/security/advisories/GHSA-rv3x-xq3r-8j9hThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.