Sender spoofing via malformed From header parsing
Published May 14, 2025 · Updated Apr 13, 2026
Address parsing in Thunderbird 128 before 128.10.1 and Thunderbird 138 before 138.0.1 allows remote attackers to spoof email senders. The From-header address parser accepts an invalid value containing multiple apparent addresses and selects the attacker-controlled address as the sender instead of rejecting the malformed field. Exploitation requires a mail server that accepts the invalid From header; the resulting message misrepresents sender identity without altering mailbox data.
Summary
What happened
Address parsing in Thunderbird 128 before 128.10.1 and Thunderbird 138 before 138.0.1 allows remote attackers to spoof email senders. The From-header address parser accepts an invalid value containing multiple apparent addresses and selects the attacker-controlled address as the sender instead of rejecting the malformed field. Exploitation requires a mail server that accepts the invalid From header; the resulting message misrepresents sender identity without altering mailbox data.
The record
- CVE
- CVE-2025-3875
- Published
- May 14, 2025
- Updated
- Apr 13, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-290, T1036
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 14, 2025CVE publishedPublication date reported by the CVE source.
- Apr 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Published CVSS scores
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Attacks
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Technologies
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