Executive Summary

Memory safety bugs in Firefox 133, Thunderbird 133, and their ESR 115.18/128.5 releases could lead to memory corruption and potentially arbitrary code execution. The issue was mitigated in Firefox 134, ESR 128.6/115.19, and Thunderbird 134/128.6. No current CISA KEV listing.

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Authoritative CVE Metadata - CVSS Base Score: 6.5 (MEDIUM) - Published: 2025-01-07T16:15:38.860 - Last Modified: 2026-10-05T15:10:00.590

Original Description: Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR 115.18, Firefox ESR 128.5, Thunderbird 115.18, and Thunderbird 128.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Firefox ESR 115.19, Thunderbird 134, and Thunderbird 128.6.

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