Vulnerability · Published Oct 15, 2026 · Assigned by Checkmarx
CVE-2026-108082Symfony: ReDoS in HeaderUtils::split() Reachable Through the Cache-Control Request Header
High 8.7
In plain English
A high-severity regular-expression denial of service in symfony from sensiolabs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | symfony | no fix listed | DEBIAN-CVE-2026-108082 |
| Debian:13 | symfony | 6.4.49+dfsg-0+deb13u1 | DEBIAN-CVE-2026-108082 |
| Debian:14 | symfony | 7.4.19+dfsg-1 | DEBIAN-CVE-2026-108082 |
| Packagist | symfony/http-foundation | 5.4.54 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/http-foundation | 6.4.46 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/http-foundation | 7.4.19 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/http-foundation | 8.1.7 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/symfony | 5.4.54 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/symfony | 8.1.7 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/symfony | 7.4.19 | GHSA-r925-mgvr-h9cc |
| Packagist | symfony/symfony | 6.4.46 | GHSA-r925-mgvr-h9cc |
| Ubuntu:26.04:LTS | symfony | no fix listed | UBUNTU-CVE-2026-108082 |
| Ubuntu:26.10 | symfony | no fix listed | UBUNTU-CVE-2026-108082 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| sensiolabs | symfony | v4.1.0-BETA1 – before v5.4.54v6.0.0-BETA1 – before v6.4.46v7.0.0-BETA1 – before v7.4.19v8.0.0-BETA1 – before v8.1.7 |
Weakness: CWE-1333 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References
- https://github.com/symfony/symfony/pull/66048 patch
- https://github.com/symfony/symfony/pull/66491 patch
- https://github.com/symfony/symfony/security/advisories/GHSA-r925-mgvr-h9cc vendor-advisory
- https://symfony.com/blog/cve-2026-108082-redos-in-headerutils-split-reachable-through-the-cache-control-request-header vendor-advisory