CVE-2026-48784 Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Generated URL Collapses Off-Route Under RFC 3986 Normalization

What is CVE-2026-48784?

CVE-2026-48784 is a medium-severity vulnerability in Sensiolabs Symfony, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, UrlGenerator::doGenerate() used strtr() dot-segment encoding that skipped every other chained ../ or ./ segment, allowing attacker-controlled route parameters to generate URLs that collapse to a different path under RFC 3986 normalization. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.

Weakness: CWE-601, CWE-172

Which versions are affected by CVE-2026-48784?

16 open source packages ship an affected version, including symfony/routing and symfony/symfony. It affects 1 product.

Products include Sensiolabs Symfony.

How do I fix CVE-2026-48784?

Upgrade symfony/routing to a fixed version for your release line: 5.4.53, 6.4.41, 7.4.13 or 8.0.13.

Is CVE-2026-48784 being exploited?

There is no known exploitation of CVE-2026-48784 in the wild and no public exploit code.

Other vulnerabilities in Sensiolabs Symfony

• CVE-2019-11325 Improper Input Validation in Symfony Critical 9.8
• CVE-2017-11365 Symfony Incorrect Access Control Critical 9.8
• CVE-2019-10913 Invalid HTTP method overrides allow possible XSS or other attacks in Symfony Critical 9.8
• CVE-2018-11407 Symfony Authentication Bypass Critical 9.8
• CVE-2016-2403 Symfony Authentication Bypass Critical 9.8

All Sensiolabs Symfony vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-48784, GHSA-h5x3-xfc9-m39h, UBUNTU-CVE-2026-48784.