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CVE-2023-23603

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

MEDIUM
6.5
CVSS Score
Published: June 2, 2023 at 12:00 AM UTC
Updated: June 17, 2026 at 05:37 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Firefox· Mozilla
95%
v < 109
Affected range stops below 109, so it looks safe — our inference, not a vendor statement
Affected range stops below 109.0, so it looks safe — our inference, not a vendor statement
Firefox ESR· Mozilla
95%
v < 102.7
Affected range stops below 102.7, so it looks safe — our inference, not a vendor statement
Thunderbird· Mozilla
95%
v < 102.7
Affected range stops below 102.7, so it looks safe — our inference, not a vendor statement

References (4)

Issue TrackingPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1800832
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2023-01/
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2023-02/
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2023-03/

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfoCWE-770

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