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CVE-2026-108082: symfony

Severity

8.7 (HIGH)

Vendor

SENSIOLABS

Affected versions

v4.1.0-BETA1 through before v5.4.54; v6.0.0-BETA1 through before v6.4.46; v7.0.0-BETA1 through before v7.4.19

Patch status

Unknown

Published

2026-10-15T15:17:22.583

Why it matters

This matters because the issue affects identity or token handling. Successful exploitation could allow unauthorized authentication, client manipulation, or access to protected services.

Recommended admin actions

• Review and patch based on exposure, asset criticality, and business impact.
• Compare installed versions against the affected version range in the advisory.

Technical summary

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to versions 5.4.54, 6.4.46, 7.4.19, and 8.1.7, HeaderUtils::split() parsed header values with a pattern whose token alternative also matched whitespace, followed by a (?<!\s) lookbehind. A run of whitespace placed before a separator could be divided among the iterations of the enclosing repetition in exponentially many ways, and the engine tried all of them before settling. HeaderBag calls it for the Cache-Control header whenever a Request is built, so any application handling HTTP requests is reachable, with no authentication. A single request carrying such a header costs close to a second of CPU (813 ms for a run of 17 spaces in an 8 KB header on PHP 8.5, doubling with each extra space). From 18 spaces on, preg_match_all() gives up at pcre.backtrack_limit and split() returns an empty array, so every directive of the header is silently dropped. This issue affects symfony/http-foundation v4.1.0-BETA1 through v5.4.53, v6.0.0-BETA1 through v6.4.45, v7.0.0-BETA1 through v7.4.18, and v8.0.0-BETA1 through v8.1.6.

View the official NVD record for CVE-2026-108082

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.