CVE-2026-57527Network attack vector

Code execution via unfiltered ViewState deserialization

Published Jun 26, 2026 · Updated Jun 26, 2026

Insecure deserialization in the ZAP ViewState add-on before 4 allows attackers controlling a proxied server to execute code in ZAP. The JSFViewState.decode() method Base64-decodes javax.faces.ViewState and passes the bytes to ObjectInputStream.readObject() with no filter or type restriction. Attackers must control a response selected in the Desktop UI; the alpha add-on is not installed by default, and ZAP reports no reproduced RCE on 2.17.

CVSS severity8.7
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in the ZAP ViewState add-on before 4 allows attackers controlling a proxied server to execute code in ZAP. The JSFViewState.decode() method Base64-decodes javax.faces.ViewState and passes the bytes to ObjectInputStream.readObject() with no filter or type restriction. Attackers must control a response selected in the Desktop UI; the alpha add-on is not installed by default, and ZAP reports no reproduced RCE on 2.17.

The record

CVE
CVE-2026-57527
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
ZAP
Product
ZAP Add-ons
Classifications
CWE-502, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ZAP · ZAP Add-onsversion=0 <4

Published CVSS scores

8.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.7VulnCheckCVSS: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 describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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