CVE-2026-4687

Advisory lineage Upstream: 0 Downstream: 41
Modified
Published: 24 Mar 2026, 12:30
Last modified:15 Jul 2026, 00:49

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.6 CRITICAL
v3.1 (cve.org)
EPSS Score
0.54% LOW
1% probability +0.11%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

24 Mar 2026, 12:30
Published
Vulnerability first disclosed
15 Jul 2026, 00:49
Last Modified
Vulnerability information updated

Description

Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS Metrics

  • v3.1•HIGH•Score: 8.6CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
  • v3.1•CRITICAL•Score: 9.6CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.54%• Percentile: 41%

Techniques & Countermeasures

  • CWE-754•Improper Check for Unusual or Exceptional Conditions

    The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

  • CWE-120•Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

    The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

  • CWE-501•Trust Boundary Violation

    The product mixes trusted and untrusted data in the same data structure or structured message.

Affected Systems

  • mozilla•firefox

    ≥ unspecified, < 149 | < 115.34.0 | < 149.0 | ≥ 128.0, < 140.9.0

  • mozilla•firefox_esr

    ≥ unspecified, < 115.34 | ≥ unspecified, < 140.9

  • mozilla•thunderbird

    ≥ unspecified, < 149 | ≥ unspecified, < 140.9

References (34)