CVE-2026-108082
Symfony is a PHP framework for web and console applications and a set of reusable PHP components.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| composer | symfony/http-foundation | >= 6.0.1, < 6.4.46 | 6.4.46 |
| composer | symfony/symfony | >= 6.0.1, < 6.4.46 | 6.4.46 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-r925-mgvr-h9cc
- https://github.com/symfony/symfony/security/advisories/GHSA-r925-mgvr-h9cc
- https://nvd.nist.gov/vuln/detail/CVE-2026-108082
- https://github.com/symfony/symfony/pull/66048
- https://github.com/symfony/symfony/pull/66491
- https://github.com/symfony/symfony/commit/343a1772ce6ac03e48b228d2d7168d19750e3f36
- https://github.com/symfony/symfony/commit/9ffa802e5d7e9fb8ba95eeefd27e863e83b1baca
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-foundation/CVE-2026-108082.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-108082.yaml
- https://github.com/symfony/symfony/releases/tag/v5.4.54
- https://github.com/symfony/symfony/releases/tag/v6.4.48
- https://github.com/symfony/symfony/releases/tag/v7.4.21
- https://github.com/symfony/symfony/releases/tag/v8.1.9
- https://symfony.com/blog/cve-2026-108082-redos-in-headerutils-split-reachable-through-the-cache-control-request-header
- https://symfony.com/cve-2026-108082