SB20260425215 - Input validation error in Preact

Description

This security bulletin contains information about 1 vulnerability.

1) Input validation error (CVE-ID: CVE-2026-22028)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to inject HTML.

The vulnerability exists due to improper input validation in the Preact render tree handling of children when processing unmodified user-controlled values from external data sources that are assumed to be strings but are actual JavaScript objects. A remote attacker can supply a specially crafted JSON payload to inject HTML.

Arbitrary script execution may be possible if the injected HTML is not otherwise constrained. Exploitation requires insecure type handling or a compromised data source, and the issue was not present in preact-render-to-string.

Remediation

Install update from vendor's website.

References

• https://github.com/preactjs/preact/security/advisories/GHSA-36hm-qxxp-pg3m
• https://github.com/advisories/GHSA-36hm-qxxp-pg3m