# CVE-2026-108082: Symfony HTTP Foundation ReDoS in HeaderUtils::split()

Source: https://junglewise.ai/threats/cve-2026-108082-symfony-is-a-php-framework-for-web-and-console-applications-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-108082 · Severity: high · CVSS 4 · Published 2026-10-15

Symfony's HTTP Foundation library parses HTTP headers using a regular expression vulnerable to catastrophic backtracking when processing whitespace-heavy input. An attacker can send a specially crafted Cache-Control header that causes the application to consume excessive CPU, leading to denial of service. Any web application using Symfony to handle HTTP requests is affected without requiring authentication.

Technologies: [symfony/http-foundation (Packagist)](https://junglewise.ai/threats/technologies/symfony-http-foundation), [symfony/symfony (Packagist)](https://junglewise.ai/threats/technologies/symfony-symfony), [Symfony Http Foundation](https://junglewise.ai/threats/technologies/http-foundation). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist), [Symfony](https://junglewise.ai/threats/vendors/symfony).

## Quick answers

**Is CVE-2026-108082 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-108082 being exploited in the wild.

**How severe is CVE-2026-108082?** High severity, with a CVSS score of 4, published 15 October 2026.

**Which products and versions are affected?** symfony/http-foundation (Packagist) >= 6.0.1, < 6.4.46, ECOSYSTEM:introduced=6.0.1,fixed=6.4.46; symfony/symfony (Packagist) >= 6.0.1, < 6.4.46, ECOSYSTEM:introduced=6.0.1,fixed=6.4.46; Symfony Http Foundation 4.1.0-BETA1 through 5.4.53; 6.0.0-BETA1 through 6.4.45; 7.0.0-BETA1 through 7.4.18; 8.0.0-BETA1 through 8.1.6.

**Is there a fix for CVE-2026-108082?** Yes. symfony/http-foundation (Packagist): upgrade to 6.4.46 or later; symfony/symfony (Packagist): upgrade to 6.4.46 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-108082 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-108082?** Check whether you run symfony/http-foundation (Packagist), symfony/symfony (Packagist) or Symfony Http Foundation at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- symfony/http-foundation (Packagist): upgrade to 6.4.46 or later

  ```sh
  composer require symfony/http-foundation:^6.4.46
  ```

- symfony/symfony (Packagist): upgrade to 6.4.46 or later

  ```sh
  composer require symfony/symfony:^6.4.46
  ```


## Technical details

The HeaderUtils::split() function uses a regex pattern with alternation and lookahead/lookbehind assertions that allows exponential interpretation of whitespace characters before a separator. A run of N spaces can be divided among quantifier iterations in 2^N ways, forcing the regex engine to backtest all paths. This causes exponential CPU consumption (roughly doubling per additional space); beyond the pcre.backtrack_limit threshold (18+ spaces), parsing silently fails and returns an empty array, causing header directives to be dropped.

## Affected products

- Symfony HTTP Foundation 4.1.0-BETA1 through 5.4.53; 6.0.0-BETA1 through 6.4.45; 7.0.0-BETA1 through 7.4.18; 8.0.0-BETA1 through 8.1.6

## Identifiers

- CVE-2026-108082
- GHSA-r925-mgvr-h9cc

## Timeline

- 2026-10-15: disclosed: CVE-2026-108082 published
- 2026-09-14: patched: Fix merged in GitHub PR #66048

## References

- [https://packagist.org/packages/symfony/http-foundation](https://packagist.org/packages/symfony/http-foundation)
- [https://github.com/symfony/symfony/pull/66048](https://github.com/symfony/symfony/pull/66048)

## Related threats

- [Symfony http-foundation HTTP method matching bypass](https://junglewise.ai/threats/cve-2026-118514-in-symfony-http-foundation-prior-to-versions-5-4-56-6-4-50-7-4)
- [Symfony YAML stack exhaustion in inline lexer](https://junglewise.ai/threats/cve-2026-109413-in-symfony-yaml-prior-to-versions-5-4-54-6-4-45-7-4-18-and-8-1-6)
- [Symfony Routing improper dot-segment encoding in UrlGenerator](https://junglewise.ai/threats/cve-2026-48784-symfony-routing-improper-dot-segment-encoding-in-urlgenerator)
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