CVE-2026-57527: zaproxy zap-extensions · Deserialization of Untrusted Data
Affects zaproxy zap-extensionsSource CVE Database V5
Not known to be exploited · CVSS 8.7 High : upgrade to 4 soon.
Data as of 8 Nov 2026, 14:19 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 8.7 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 8.8 |
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 26 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 8 Nov 2026.
What to do
Upgrade zaproxy zap-extensions to 4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| zaproxyzap-extensions | Affected
| Fixed in– |
GitHubzap-extensionspkg:github/zap-extensionsOther 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
If you cannot patch yet, avoid proxying untrusted web servers that may return malicious ViewState parameters.
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.
References
- zaproxy.org/blog/2026-06-24-java-deserialization-vulnerability-in-zap-viewstate-addon/ (opens in a new tab)
- github.com/zaproxy/zap-extensions/releases/tag/viewstate-v4 (opens in a new tab)
- github.com/zaproxy/zap-extensions/pull/7481 (opens in a new tab)
- github.com/zaproxy/zap-extensions/commit/ac6c3f94d38505bc0facea286a4d3728044c6e5c (opens in a new tab)
- vulncheck.com/advisories/zap-viewstate-add-on-insecure-deserialization-via-jsfviewstate-decode (opens in a new tab)