CVE-2026-57527
ZAP ViewState Add-on Insecure Deserialization via JSFViewState.decode()
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.7
ZAP ViewState Add-on Insecure Deserialization via JSFViewState.decode()
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.
- Record
CVE-2026-57527- CVSS 4.0
- 8.7 High
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 - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-08
EUVDEUVD-2026-39777
8.7
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.
- Record
EUVD-2026-39777- CVSS 4.0
- 8.7 High
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 - Updated
- 2026-11-08
GitHub AdvisoriesGHSA-grq4-7pwr-9rmp
8.7
Zed Attack Proxy (ZAP) ViewState add-on before version 4 contains an insecure deserialization...
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.
- Record
GHSA-grq4-7pwr-9rmp- CVSS 4.0
- 8.7 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
NVD
8.7
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.
- Record
CVE-2026-57527- CVSS 4.0
- 8.7 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
OSV
8.7
ZAP ViewState Add-on Insecure Deserialization via JSFViewState.decode()
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.
- Record
CVE-2026-57527- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-502
- Updated
- 2026-11-09
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| references | OSV | |
| references | CVE List | |
| facts | EUVD | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-57527 is a high vulnerability (CVSS 8.7) in Zaproxy Zap-extensions, published June 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.68%, the 52nd percentile. No source names a fixed version.
References
zaproxy.org/blog/2026-06-24-java-deserialization-vulnerability-in-zap-viewstate-addon
github.com/zaproxy/zap-extensions/releases/tag/viewstate-v4
github.com/zaproxy/zap-extensions/pull/7481
github.com/zaproxy/zap-extensions/commit/ac6c3f94d38505bc0facea286a4d3728044c6e5c
vulncheck.com/advisories/zap-viewstate-add-on-insecure-deserialization-via-jsfviewstate-decode
nvd.nist.gov/vuln/detail/CVE-2026-57527
github.com/advisories/GHSA-grq4-7pwr-9rmp
github.com/CVEProject/cvelistV5/tree/main/cves/2026/57xxx/CVE-2026-57527.json
github.com/zaproxy/zap-extensions