CVE-2026-57527: Deserialization of Untrusted Data in zaproxy zap-extensions
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.
AI Analysis
Technical Summary
CVE-2026-57527 is an insecure deserialization vulnerability in the ZAP ViewState add-on prior to version 4. The vulnerability occurs because the JSFViewState.decode() method base64-decodes the javax.faces.ViewState HTTP response parameter and passes it directly to ObjectInputStream.readObject() without applying deserialization filters, allowlists, or type restrictions. This allows an attacker who controls a proxied web server to embed a malicious serialized Java object that is deserialized within the ZAP JVM, leading to arbitrary code execution when the Desktop UI renders the ViewState panel.
Potential Impact
Successful exploitation allows unauthenticated attackers controlling a proxied web server to execute arbitrary code within the ZAP JVM environment. This can lead to full compromise of the host running the vulnerable ZAP Desktop UI. The vulnerability has a high CVSS 4.0 score of 8.7, reflecting network attack vector, low attack complexity, no privileges required, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should avoid proxying untrusted web servers that might return malicious ViewState parameters or disable the ViewState add-on if possible. Monitor vendor channels for updates and apply patches promptly once released.
CVE-2026-57527: Deserialization of Untrusted Data in zaproxy zap-extensions
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.
CVSS v4.0
Score 8.7high
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-57527 is an insecure deserialization vulnerability in the ZAP ViewState add-on prior to version 4. The vulnerability occurs because the JSFViewState.decode() method base64-decodes the javax.faces.ViewState HTTP response parameter and passes it directly to ObjectInputStream.readObject() without applying deserialization filters, allowlists, or type restrictions. This allows an attacker who controls a proxied web server to embed a malicious serialized Java object that is deserialized within the ZAP JVM, leading to arbitrary code execution when the Desktop UI renders the ViewState panel.
Potential Impact
Successful exploitation allows unauthenticated attackers controlling a proxied web server to execute arbitrary code within the ZAP JVM environment. This can lead to full compromise of the host running the vulnerable ZAP Desktop UI. The vulnerability has a high CVSS 4.0 score of 8.7, reflecting network attack vector, low attack complexity, no privileges required, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should avoid proxying untrusted web servers that might return malicious ViewState parameters or disable the ViewState add-on if possible. Monitor vendor channels for updates and apply patches promptly once released.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-06-24T15:58:58.538Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3e95a96e08203f7da55afb
Added to database: 06/26/2026, 15:07:21 UTC
Last enriched: 06/26/2026, 15:36:53 UTC
Last updated: 06/26/2026, 18:34:18 UTC
Views: 3
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.