CVE-2026-22028: preactjs preact · Type Confusion
Affects preactjs preactSource CVE Database V5
Not known to be exploited · CVSS 7.2 High · fixed in 10.28.2 : patch preactjs preact soon.
Data as of 26 Oct 2026, 06:26 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 10.28.2, 10.27.3, 10.26.10
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:UExploitation evidence
Disclosed: evidence found.
CVE published 8 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
Upgrade preact and preactjs/preact to 10.28.2, 10.27.3 or 10.26.10.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| preactjspreact | Affected
| Fixed in
|
npmpreactjs/preactpkg:npm/preactjs/preactOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should prioritize upgrading Preact to versions 10.26.10, 10.27.3, or 10.28.2 to apply the official patches that restore strict type checking. For environments where immediate upgrade is not feasible, implement strict input validation and type checking on all data entering the render tree, ensuring that only strings or properly sanitized VNodes are passed. Sanitize and validate all user-controllable data sources, including APIs, databases, and local storage, to prevent injection of malicious objects. Employ Content Security Policy (CSP) headers with strict script-src directives to mitigate the impact of any injected scripts. Conduct thorough code reviews and audits to identify unsafe data handling patterns. Implement runtime monitoring for anomalous DOM manipulations or script injections. Educate development teams on secure coding practices related to client-side rendering frameworks. Finally, maintain an inventory of applications using Preact and verify their versions and data handling methods to assess exposure.
Description
Preact, a lightweight web development framework, JSON serialization protection to prevent Virtual DOM elements from being constructed from arbitrary JSON. A regression introduced in Preact 10.26.5 caused this protection to be softened. In applications where values from JSON payloads are assumed to be strings and passed unmodified to Preact as children, a specially-crafted JSON payload could be constructed that would be incorrectly treated as a valid VNode. When this chain of failures occurs it can result in HTML injection, which can allow arbitrary script execution if not mitigated by CSP or other means. Applications using affected Preact versions are vulnerable if they meet all of the following conditions: first, pass unmodified, unsanitized values from user-modifiable data sources (APIs, databases, local storage, etc.) directly into the render tree; second assume these values are strings but the data source could return actual JavaScript objects instead of JSON strings; and third, the data source either fails to perform type sanitization AND blindly stores/returns raw objects interchangeably with strings, OR is compromised (e.g., poisoned local storage, filesystem, or database). Versions 10.26.10, 10.27.3, and 10.28.2 patch the issue. The patch versions restore the previous strict equality checks that prevent JSON-parsed objects from being treated as valid VNodes. Other mitigations are available for those who cannot immediately upgrade. Validate input types, cast or validate network data, sanitize external data, and use Content Security Policy (CSP).