Summary
Symfony Incorrect Access Control
FragmentListener in the HttpKernel component in Symfony 2.3.19 through 2.3.28, 2.4.9 through 2.4.10, 2.5.4 through 2.5.11, and 2.6.0 through 2.6.7, when ESI or SSI support enabled, does not check if the _controller attribute is set, which allows remote attackers to bypass URL signing and security rules by including (1) no hash or (2) an invalid hash in a request to /_fragment.
This issue has been fixed in Symfony 2.3.29, 2.5.12, and 2.6.8. Note that no fixes are provided for Symfony 2.4 as it's not maintained anymore.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
symfony/http-kernel to 2.3.29 or later; symfony/http-kernel to 2.5.12 or later; symfony/http-kernel to 2.6.8 or later; symfony/symfony to 2.3.29 or later; symfony/symfony to 2.5.12 or later; symfony/symfony to 2.6.8 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2015-4050? CVE-2015-4050 is a medium-severity security vulnerability in symfony/http-kernel (composer), affecting versions >= 2.3.19, < 2.3.29. It is fixed in 2.3.29, 2.5.12, 2.6.8.
- Which packages are affected by CVE-2015-4050?
symfony/http-kernel(composer) (versions >= 2.3.19, < 2.3.29)symfony/symfony(composer) (versions >= 2.3.19, < 2.3.29)
- Is there a fix for CVE-2015-4050? Yes. CVE-2015-4050 is fixed in 2.3.29, 2.5.12, 2.6.8. Upgrade to this version or later.
- Is CVE-2015-4050 exploitable, and should I be worried? Whether CVE-2015-4050 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2015-4050 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2015-4050?
- Upgrade
symfony/http-kernelto 2.3.29 or later - Upgrade
symfony/http-kernelto 2.5.12 or later - Upgrade
symfony/http-kernelto 2.6.8 or later - Upgrade
symfony/symfonyto 2.3.29 or later - Upgrade
symfony/symfonyto 2.5.12 or later - Upgrade
symfony/symfonyto 2.6.8 or later
- Upgrade