Description
Zed Attack Proxy (ZAP) ViewState add-on before version 4 contains an insecure deserialization vulnerability that allows attackers who control a proxied web server to achieve arbitrary code execution by embedding a malicious serialized Java object in the javax.faces.ViewState HTTP response parameter. The JSFViewState.decode() method base64-decodes the ViewState value and passes it directly to ObjectInputStream.readObject() without a deserialization filter, allowlist, or type restriction, causing the malicious object to be deserialized within the ZAP JVM when the Desktop UI renders the ViewState panel.
Severity (CVSS)
| Base score | 8.7 |
|---|---|
| Severity | High |
| Version | CVSS 4.0 |
| Vector | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| Provided by | CNA |
Weaknesses
- CWE-502 — Deserialization of Untrusted Data
Affected products
| Vendor | Product | Versions |
|---|---|---|
| zaproxy | zap-extensions | 0 to <4 |
References
- https://www.zaproxy.org/blog/2026-06-24-java-deserialization-vulnerability-in-zap-viewstate-addon/ (technical-description vendor-advisory)
- https://github.com/zaproxy/zap-extensions/releases/tag/viewstate-v4 (release-notes)
- https://github.com/zaproxy/zap-extensions/pull/7481 (issue-tracking)
- https://github.com/zaproxy/zap-extensions/commit/ac6c3f94d38505bc0facea286a4d3728044c6e5c (patch)
- https://www.vulncheck.com/advisories/zap-viewstate-add-on-insecure-deserialization-via-jsfviewstate-decode (third-party-advisory)
Generated from the official CVE List on 27 Jun 2026 07:02 UTC.