What’s Vulnerable › Vulnerabilities

CVE-2017-18343

• Severity: medium (CVSS 6.1 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2018-07-20 · updated 2026-06-17
• Weakness: CWE-79

Description

The debug handler in Symfony before v2.7.33, 2.8.x before v2.8.26, 3.x before v3.2.13, and 3.3.x before v3.3.6 has XSS via an array key during exception pretty printing in ExceptionHandler.php, as demonstrated by a /_debugbar/open?op=get URI. NOTE: the vendor's position is that this is not a vulnerability because the debug tools are not intended for production use. NOTE: the Symfony Debug component is used by Laravel Debugbar

Affected products

• symfony: before 2.7.33; from 2.8.0 before 2.8.26; from 3.0.0 before 3.2.13; from 3.3.0 before 3.3.6 — fixed in 2.7.33, 2.8.26, 3.2.13, 3.3.6

How to fix

Upgrade to a fixed version: symfony 2.7.33, 2.8.26, 3.2.13, 3.3.6. Check the vendor advisory for mitigations.

References

• https://github.com/barryvdh/laravel-debugbar/issues/850
• https://github.com/symfony/debug/pull/7/commits/e48bda29143bd1a83001780b4a78e483822d985c
• https://github.com/symfony/symfony/issues/27987
• https://github.com/symfony/symfony/pull/23684
• https://github.com/barryvdh/laravel-debugbar/issues/850
• https://github.com/symfony/debug/pull/7/commits/e48bda29143bd1a83001780b4a78e483822d985c
• https://github.com/symfony/symfony/issues/27987
• https://github.com/symfony/symfony/pull/23684

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