Integer overflow in libmime buffer growth could lead to heap corruption

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-110247
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-13 19:18:49 UTC
Updated2026-10-20 18:17:17 UTC
DescriptionSeveral 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.

Risk And Classification

Primary CVSS: v3.1 8.4 HIGH from ADP

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001710000 probability, percentile 0.061480000 (date 2026-10-20)

Problem Types: CWE-190 | CWE-190 CWE-190 Integer Overflow or Wraparound

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Thunderbird unaffected 158 * rpm Not specified

References

ReferenceSourceLinkTags
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-109 [email protected] www.mozilla.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Ahmed Albalawi (en)

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