Summary
Symfony vulnerable to denial of service via a malicious HTTP Host header
All 2.0.X, 2.1.X, 2.2.X, 2.3.X, 2.4.X, and 2.5.X versions of the Symfony HttpFoundation component are affected by this security issue.
This issue has been fixed in Symfony 2.3.19, 2.4.9, and 2.5.4. Note that no fixes are provided for Symfony 2.0, 2.1, and 2.2 as they are not maintained anymore.
Description
When an arbitrarily long hostname is sent by a client, its parsing in Request::getHost() can lead to a DoS attack, due to the way we validate the hostname via a regular expression.
Resolution
The regular expression used to parse and validate the hostname from the HTTP request has been modified to avoid too much sensitivity to the submitted value length.
The patch for this issue is available here: https://github.com/symfony/symfony/pull/11828
Impact
A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use. Typical impact: denial of service when input is crafted to trigger backtracking.
CVE-2014-5244 has a CVSS score of 7.5 (High). 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 (2.3.19, 2.4.9, 2.5.4); upgrading removes the vulnerable code path.
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.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
symfony/http-foundation to 2.3.19 or later; symfony/http-foundation to 2.4.9 or later; symfony/http-foundation to 2.5.4 or later; symfony/symfony to 2.3.19 or later; symfony/symfony to 2.4.9 or later; symfony/symfony to 2.5.4 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2014-5244? CVE-2014-5244 is a high-severity inefficient regular expression (ReDoS) vulnerability in symfony/http-foundation (composer), affecting versions >= 2.0.0, < 2.3.19. It is fixed in 2.3.19, 2.4.9, 2.5.4. A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use.
- How severe is CVE-2014-5244? CVE-2014-5244 has a CVSS score of 7.5 (High). 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.
- Which packages are affected by CVE-2014-5244?
symfony/http-foundation(composer) (versions >= 2.0.0, < 2.3.19)symfony/symfony(composer) (versions >= 2.0.0, < 2.3.19)
- Is there a fix for CVE-2014-5244? Yes. CVE-2014-5244 is fixed in 2.3.19, 2.4.9, 2.5.4. Upgrade to this version or later.
- Is CVE-2014-5244 exploitable, and should I be worried? Whether CVE-2014-5244 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-2014-5244 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-2014-5244?
- Upgrade
symfony/http-foundationto 2.3.19 or later - Upgrade
symfony/http-foundationto 2.4.9 or later - Upgrade
symfony/http-foundationto 2.5.4 or later - Upgrade
symfony/symfonyto 2.3.19 or later - Upgrade
symfony/symfonyto 2.4.9 or later - Upgrade
symfony/symfonyto 2.5.4 or later
- Upgrade