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CVE-2020-5274

Exceptions displayed in non-debug configurations in Symfony

4.6 MediumFix available

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

1.20%Up 0.4 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 4.6

Exceptions displayed in non-debug configurations in Symfony

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
CVE-2020-5274
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Weakness
CWE-209
Updated
2026-11-02
EUVDEUVD-2020-0350 4.6

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
EUVD-2020-0350
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-m884-279h-32v2 4.6

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.

Record
GHSA-m884-279h-32v2
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Weakness
CWE-209
Updated
2026-11-02
NVD 4.6

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
CVE-2020-5274
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CVSS 2.0
5.5 MediumAV:N/AC:L/Au:S/C:P/I:P/A:N
Weakness
CWE-209
Updated
2026-11-02
OSV 5.4

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
CVE-2020-5274
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2020-5274 5.4

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
DEBIAN-CVE-2020-5274
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-m884-279h-32v2 4.6

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.

Record
GHSA-m884-279h-32v2
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Weakness
CWE-209
Updated
2026-11-02
OSVBIT-symfony-2020-5274 No score

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the ErrorHandler rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

Record
BIT-symfony-2020-5274
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
symfony/error-handler
Packagist
 4.4.0 up to 4.4.4
4.4.4
symfony/error-handler
Packagist
 5.0.0 up to 5.0.4
5.0.4
symfony/symfony
Packagist
 4.4.0 up to 4.4.4
4.4.4
symfony/symfony
Packagist
 5.0.0 up to 5.0.4
5.0.4
symfony
Bitnami
 4.4.0 up to 4.4.4, 5.0.0 up to 5.0.4
4.4.45.0.4
symfony
Debian:12
 before 4.4.8-1
4.4.8-1
symfony
Debian:13
 before 4.4.8-1
4.4.8-1
symfony
Debian:14
 before 4.4.8-1
4.4.8-1
symfony/error-handler
Packagist
 4.4.0 up to 4.4.4, plus listed versions
v4.4.0v4.4.1v4.4.2v4.4.3
4.4.4
symfony/error-handler
Packagist
 5.0.0 up to 5.0.4, plus listed versions
v5.0.0v5.0.1v5.0.2v5.0.3
5.0.4
symfony/symfony
Packagist
 4.4.0 up to 4.4.4, plus listed versions
v4.4.0v4.4.1v4.4.2v4.4.3
4.4.4
symfony/symfony
Packagist
 5.0.0 up to 5.0.4, plus listed versions
v5.0.0v5.0.1v5.0.2v5.0.3
5.0.4

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-5274 is a medium vulnerability (CVSS 4.6) in Sensiolabs Symfony, published March 30, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.20%, the 68th percentile. Fixed in symfony/error-handler 4.4.4.

References

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