# CVE-2026-57527: ZAP ViewState Add-on Insecure Deserialization via JSFViewState.decode()

> Attackers controlling a proxied server can achieve arbitrary code execution in ZAP by sending malicious serialized Java objects in ViewState parameters.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 26 Jun 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-grq4-7pwr-9rmp

## What is CVE-2026-57527?

CVE-2026-57527 is a high-severity unsafe deserialization vulnerability in zaproxy zap-extensions, published on 26 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-57527?


## How do I fix CVE-2026-57527?

No fix has been published for CVE-2026-57527 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57527 being exploited?

There is no known exploitation of CVE-2026-57527 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57527 and fix it if it is affected.

What it is: CVE-2026-57527 is a high-severity unsafe deserialization vulnerability in zaproxy zap-extensions, published on 26 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-57527 in the wild and no public exploit code.

Affected product: zaproxy zap-extensions. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-57527/ (Markdown: https://insights.sbomify.com/CVE-2026-57527/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57527
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57527
- OSV: https://osv.dev/vulnerability/CVE-2026-57527

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57527/
Summaries are generated and may contain mistakes; the official description above is the record.