Home/CVE/Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
CVE

CVE-2026-3889

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

MEDIUM · CVSS 6.5 EPSS 0.00034
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-451User Interface (UI) Misrepresentation of Critical Information
▤

Affected Products & Versions

2
mozilla thunderbird< 140.9.0
mozilla thunderbird< 149.0
▣

Scoring & Timeline

6.5
MEDIUM · CVSS v3.1 · security@mozilla.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Mar 2026 · 09:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

15
suse-csafopenSUSE-SU-2026:20664-1
suse-csafSUSE-SU-2026:1163-1
suse-csafopenSUSE-SU-2026:10447-1
rhsaRHSA-2026:8286Important
rhsaRHSA-2026:8287Important
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.mozilla.org/show_bug.cgi?id=2020723Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-23/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-24/Vendor Advisory
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