What is CVE-2020-5274?

CVE-2020-5274 is a medium-severity security vulnerability in symfony/error-handler (composer), affecting versions >= 4.4.0, < 4.4.4. It is fixed in 4.4.4, 5.0.4.

How severe is CVE-2020-5274?

CVE-2020-5274 has a CVSS score of 4.6 (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.

Which packages are affected by CVE-2020-5274?

symfony/error-handler (composer) versions >= 4.4.0, = 4.4.0, < 4.4.4.

Is there a fix for CVE-2020-5274?

Yes. CVE-2020-5274 is fixed in 4.4.4, 5.0.4. Upgrade to this version or later.

Is CVE-2020-5274 exploitable, and should I be worried?

Whether CVE-2020-5274 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.

What actually determines whether CVE-2020-5274 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.

CVE-2020-5274 in symfony/error-handler

Q: How severe is CVE-2020-5274?

CVE-2020-5274 has a CVSS score of 4.6 (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.

Q: Which packages are affected by CVE-2020-5274?

symfony/error-handler (composer) versions >= 4.4.0, = 4.4.0, < 4.4.4.

Q: Is there a fix for CVE-2020-5274?

Yes. CVE-2020-5274 is fixed in 4.4.4, 5.0.4. Upgrade to this version or later.

Q: Is CVE-2020-5274 exploitable, and should I be worried?

Whether CVE-2020-5274 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.

Q: What actually determines whether CVE-2020-5274 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.

Q: How do I fix CVE-2020-5274?

Upgrade: symfony/error-handler to 4.4.4 or later, symfony/error-handler to 5.0.4 or later, symfony/symfony to 4.4.4 or later, symfony/symfony to 5.0.4 or later.

Summary

Exceptions displayed in non-debug configurations in Symfony

Description

When ErrorHandler renders an exception HTML page, it uses un-escaped properties from the related Exception class to render the stacktrace. The security issue comes from the fact that the stacktraces were also displayed in non-debug environments.

Resolution

The ErrorHandler class now escapes all properties coming from the related Exception, and the stacktrace is not displayed anymore in non-debug environments.

The patches for this issue are available here and here for branch 4.4.

Credits

I would like to thank Luka Sikic for reporting & Yonel Ceruto and Jérémy Derussé for fixing the issue.

Impact

CVE-2020-5274 has a CVSS score of 4.6 (Medium). The vector is network-reachable, low privileges required, and user interaction required. 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 (4.4.4, 5.0.4); upgrading removes the vulnerable code path.

Affected versions

symfony/error-handler (>= 4.4.0, < 4.4.4) symfony/error-handler (>= 5.0.0, < 5.0.4) symfony/symfony (>= 4.4.0, < 4.4.4) symfony/symfony (>= 5.0.0, < 5.0.4)

Security releases

symfony/error-handler → 4.4.4 (composer) symfony/error-handler → 5.0.4 (composer) symfony/symfony → 4.4.4 (composer) symfony/symfony → 5.0.4 (composer)

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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Remediation advice

Upgrade the following packages to resolve this vulnerability:

symfony/error-handler to 4.4.4 or later; symfony/error-handler to 5.0.4 or later; symfony/symfony to 4.4.4 or later; symfony/symfony to 5.0.4 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2020-5274? CVE-2020-5274 is a medium-severity security vulnerability in symfony/error-handler (composer), affecting versions >= 4.4.0, < 4.4.4. It is fixed in 4.4.4, 5.0.4.
How severe is CVE-2020-5274? CVE-2020-5274 has a CVSS score of 4.6 (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.
Which packages are affected by CVE-2020-5274?
- symfony/error-handler (composer) (versions >= 4.4.0, < 4.4.4)
- symfony/symfony (composer) (versions >= 4.4.0, < 4.4.4)
Is there a fix for CVE-2020-5274? Yes. CVE-2020-5274 is fixed in 4.4.4, 5.0.4. Upgrade to this version or later.
Is CVE-2020-5274 exploitable, and should I be worried? Whether CVE-2020-5274 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-2020-5274 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-2020-5274?
- Upgrade symfony/error-handler to 4.4.4 or later
- Upgrade symfony/error-handler to 5.0.4 or later
- Upgrade symfony/symfony to 4.4.4 or later
- Upgrade symfony/symfony to 5.0.4 or later