Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent heap allocations. This vulnerability was fixed in Thunderbird 158.

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History

Tue, 13 Oct 2026 20:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla thunderbird

Tue, 13 Oct 2026 18:30:00 +0000

Type Values Removed Values Added
Description Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent heap allocations. This vulnerability was fixed in Thunderbird 158.
Title Integer overflow in libmime buffer growth could lead to heap corruption
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cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-10-13T18:10:20.644Z

Reserved: 2026-10-13T18:08:37.322Z

Link: CVE-2026-110247

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-13T19:18:49.493

Modified: 2026-10-13T19:30:29.797

Link: CVE-2026-110247

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-13T19:45:18Z

Weaknesses

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