CVE-2023-23603

MEDIUM 6.5

Calls to console.log allowed bypassing Content Security Policy via format directive

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

Regular expressions used to filter out forbidden properties and values from style directives in calls to `console.log` weren't accounting for external URLs. Data could then be potentially exfiltrated from the browser. This vulnerability affects Firefox < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.

Vendor	mozilla
Product	firefox
Ecosystems	Browser JavaScript
Industries	Technology
Published	Jun 2, 2023
Last Updated	Dec 18, 2025

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Affected Versions

Mozilla / Firefox

unspecified < 109

Mozilla / Firefox ESR

unspecified < 102.7

Mozilla / Thunderbird

unspecified < 102.7

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=1800832 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2023-01/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2023-02/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2023-03/

Credits

Dan Veditz