CVE-2026-103500: Heap buffer overflow opening large email
Published Sep 30, 2026
·Updated
An attacker could cause a heap buffer overflow by getting a user to open an email that is greater than or equal to 2GB in size.
Affected Software
4 affected componentsFixes available
Mozilla Thunderbird<157
Mozilla Thunderbird<157
157
Mozilla Thunderbird<140.17
140.17
Mozilla Thunderbird<153.4
153.4
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 157 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 140.17 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 153.4 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 157
Event History
Sep 30, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·05:15 PM
Data Sourced
via MITRE·05:15 PM
Description
Data Sourced
via NVD·06:18 PM
Description
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
- CVE-2026-103500
- CVE-2026-100756
- CVE-2026-100757
- CVE-2026-100758
- CVE-2026-100759
- CVE-2026-100760
- CVE-2026-100761
- CVE-2026-100762
- CVE-2026-100763
- CVE-2026-100764
- CVE-2026-100765
- CVE-2026-100766
- CVE-2026-100767
- CVE-2026-100768
- CVE-2026-100769
- CVE-2026-100770
- CVE-2026-100771
- CVE-2026-100772
- CVE-2026-100773
- CVE-2026-100774
- CVE-2026-100775
- CVE-2026-100776
- CVE-2026-100777
- CVE-2026-100778
- CVE-2026-100779
- CVE-2026-100780
- CVE-2026-100781
- CVE-2026-100782
- CVE-2026-100783
- CVE-2026-100784
- CVE-2026-100785
- CVE-2026-100786
- CVE-2026-100787
- CVE-2026-100788
- CVE-2026-100789
- CVE-2026-100790
- CVE-2026-100791
- CVE-2026-100792
- CVE-2026-100793
- CVE-2026-100794
- CVE-2026-96869
- CVE-2026-100795
- CVE-2026-100796
- CVE-2026-100797
- CVE-2026-100798
- CVE-2026-100799
- CVE-2026-100800
- CVE-2026-100801
- CVE-2026-100802
- CVE-2026-100803
- CVE-2026-100804
- CVE-2026-100805
- CVE-2026-100806
- CVE-2026-100807
- CVE-2026-100808
- CVE-2026-100809
- CVE-2026-100810
- CVE-2026-100811
- CVE-2026-100812
- CVE-2026-100813
- CVE-2026-100814
- CVE-2026-100815
- CVE-2026-100816
- CVE-2026-100817
- CVE-2026-100818
- CVE-2026-100819
- CVE-2026-100820
- CVE-2026-100821
- CVE-2026-100822
- CVE-2026-100824
- CVE-2026-100825
- CVE-2026-100826
- CVE-2026-100828
- CVE-2026-100829
- CVE-2026-100830
- CVE-2026-100831
- CVE-2026-92035
- CVE-2026-100832
Frequently Asked Questions
1
What must an attacker do to trigger this issue?
The attacker must get a user to open an email message that is at least 2 GB in size.
2
Which Thunderbird releases contain the fix?
The issue was fixed in Thunderbird 157, Thunderbird 140.17, and Thunderbird 153.4.