CVE-2015-4050: FragmentListener in the HttpKernel component in Symfony 2.3.19 through 2.3.28, 2.4.9 through 2.4.10, 2.5.4...

Security readout for executives and security teams

This Symfony flaw can let a remote requester bypass protections around internal page fragments when ESI or SSI support is enabled. The issue affects specific Symfony 2.3, 2.4, 2.5, and 2.6 releases. Business urgency depends on whether affected applications use fragment rendering features and expose the /_fragment endpoint. Exposure is limited to applications running the listed Symfony versions with ESI or SSI enabled. Internet-facing applications using /_fragment or edge-side fragment rendering are the main concern. Environments without ESI/SSI support enabled are less likely to be affected based on the provided description. Prioritize review for public Symfony applications that use ESI, SSI, or fragment rendering. The risk is meaningful because the issue is an authorization bypass, but the available evidence does not confirm broad active exploitation or provide a standardized severity score. Mitigation focus: Identify Symfony applications in the affected 2.3, 2.4, 2.5, and 2.6 version ranges.; Apply Symfony or distribution security updates referenced by Symfony, Debian, or Fedora advisories.; Disable ESI or SSI support where it is not required..

Prepared

Jun 13, 2026, 22:39 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.