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Fencer Vulns
medium 6.1

CVE-2017-18343 json

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 dur…

published 2018-07-20 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-9468

cvss
6.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
6.1%
EPSS 6.1% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

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

Patch / fix

  • sensiolabs symfony 2.7.33, 2.8.26, 3.2.13, 3.3.6
  • symfony Debian 14, Debian 13, Debian 12 3.4.0+dfsg-1

debian advisories DEBIAN-CVE-2017-18343

Exploit prediction

6.11% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/symfony/symfony/issues/27987 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/barryvdh/laravel-debugbar/issues/850 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 6.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.