CVE-2026-103500
Heap buffer overflow opening large email
MEDIUM
6.1
CVSS Score
Published: September 30, 2026 at 05:15 PM UTC
Updated: October 21, 2026 at 05:24 PM UTC
1 product affected across 1 vendorThunderbird
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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.3%
SSVC
No known exploit
Description
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. This vulnerability was fixed in Thunderbird 157.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 140.17.0141.0 ≤ v < 153.4.0154.0 ≤ v < 157.0
Vendor states this is fixed in 140.17 (unaffected)
Vendor states this is fixed in 153.4 (unaffected)
Vendor states this is fixed in 157 (unaffected)
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
References (4)
SSVC — Action Prioritization
SSVCNo known exploitNot automatablePartial impact
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
- Attack Vector
- LOCAL
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- LOW
- Availability
- HIGH
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-787CWE-122
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