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LeafKit allows XSS with untrusted user input

Moderate severity GitHub Reviewed Published Aug 7, 2021 in vapor/leaf-kit • Updated Jun 19, 2023

Package

swift github.com/vapor/leaf-kit (Swift)

Affected versions

< 1.3.0

Patched versions

1.3.0

Description

Impact

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.

Patches

This has been patched in 1.3.0

Workarounds

Sanitise any untrusted input before passing it to Leaf and enable a CSP to block inline script and CSS data.

References

https://github.com/vapor/leaf-kit-ghsa-rv3x-xq3r-8j9h/pull/1

For more information

If you have any questions or comments about this advisory:

References

@0xTim 0xTim published to vapor/leaf-kit Aug 7, 2021
Published by the National Vulnerability Database Aug 9, 2021
Published to the GitHub Advisory Database Jun 9, 2023
Reviewed Jun 9, 2023
Last updated Jun 19, 2023

Severity

Moderate

EPSS score

0.084%
(37th percentile)

CVE ID

CVE-2021-37634

GHSA ID

GHSA-rv3x-xq3r-8j9h

Source code

Credits

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