CVE-2015-2309

All 2.0.X, 2.1.X, 2.2.X, 2.3.X, 2.4.X, 2.5.X, and 2.6.X versions of the Symfony HttpFoundation component are affected by this security issue.

This issue has been fixed in Symfony 2.3.27, 2.5.11, and 2.6.6. Note that no fixes are provided for Symfony 2.0, 2.1, 2.2, and 2.4 as they are not maintained anymore.

Description

The Symfony\Component\HttpFoundation\Request class provides a mechanism that ensures it does not trust HTTP header values coming from a "non-trusted" client. Unfortunately, it assumes that the remote address is always a trusted client if at least one trusted proxy is involved in the request; this allows a man-in-the-middle attack between the latest trusted proxy and the web server.

The following methods are impacted: getPort(), isSecure(), and getHost(), and getClientIps().

Resolution

All impacted methods now check that the remote address is trusted, which fixes the issue.

The patch for this issue is available here.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2015-2309 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.3.27, 2.5.11, 2.6.6); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2015-2309? CVE-2015-2309 is a medium-severity improper input validation vulnerability in symfony/http-foundation (composer), affecting versions >= 2.0.0, < 2.3.27. It is fixed in 2.3.27, 2.5.11, 2.6.6. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2015-2309? CVE-2015-2309 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2015-2309?
   • symfony/http-foundation (composer) (versions >= 2.0.0, < 2.3.27)
   • symfony/symfony (composer) (versions >= 2.0.0, < 2.3.27)
4. Is there a fix for CVE-2015-2309? Yes. CVE-2015-2309 is fixed in 2.3.27, 2.5.11, 2.6.6. Upgrade to this version or later.
5. Is CVE-2015-2309 exploitable, and should I be worried? Whether CVE-2015-2309 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
6. What actually determines whether CVE-2015-2309 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.
7. How do I fix CVE-2015-2309?
   • Upgrade symfony/http-foundation to 2.3.27 or later
   • Upgrade symfony/http-foundation to 2.5.11 or later
   • Upgrade symfony/http-foundation to 2.6.6 or later
   • Upgrade symfony/symfony to 2.3.27 or later
   • Upgrade symfony/symfony to 2.5.11 or later
   • Upgrade symfony/symfony to 2.6.6 or later