CVE-2026-108082 Affecting symfony package, versions <6.4.49+dfsg-0+deb13u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published18 Oct 2026
- disclosed15 Oct 2026
Introduced: 15 Oct 2026
NewCVE-2026-108082 (opens in a new tab)How to fix?
Upgrade Echo:latest symfony to version 6.4.49+dfsg-0+deb13u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream symfony package and not the symfony package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
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.
References
- https://advisory.echohq.com/cve/CVE-2026-108082
- https://github.com/symfony/symfony/pull/66048
- https://github.com/symfony/symfony/pull/66491
- https://github.com/symfony/symfony/security/advisories/GHSA-r925-mgvr-h9cc
- https://symfony.com/blog/cve-2026-108082-redos-in-headerutils-split-reachable-through-the-cache-control-request-header