CVE-2025-3875: Sender Spoofing via Malformed From Header in Thunderbird
Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value "Spoofed Name spoofed@example.com legitimate@example.com", Thunderbird treats spoofed@example.com as the actual address.
Other sources
Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value "Spoofed Name ", Thunderbird treats spoofed@example.com as the actual address. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.
— Ubuntu
Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value "Spoofed Name ", Thunderbird treats spoofed as the actual address. This vulnerability affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 138.0.1 - Upgrade
Upgrade
ubuntu/thunderbirdto a version that resolves this vulnerability.Fixed in 1:128.12.0+build1-0ubuntu0.22.04.1 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 128.10.1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1~deb12u1Fixed in 1:153.7.0esr-1~deb12u1Fixed in 1:140.12.0esr-1~deb13u1Fixed in 1:153.7.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.7.0esr-1 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 128.10.1
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the severity of CVE-2025-3875?
CVE-2025-3875 is classified as a medium severity vulnerability due to its potential for sender spoofing.
How do I fix CVE-2025-3875?
To fix CVE-2025-3875, update Mozilla Thunderbird to version 128.10.1 or 138.0.1 or later.
What versions of Thunderbird are affected by CVE-2025-3875?
CVE-2025-3875 affects versions of Mozilla Thunderbird prior to 128.10.1 and prior to 138.0.1.
What can happen if I am affected by CVE-2025-3875?
If affected by CVE-2025-3875, users may be misled by emails that appear to come from spoofed addresses.
Is there a workaround for CVE-2025-3875 before applying the patch?
There are no documented workarounds for CVE-2025-3875, so users should apply the required updates as soon as possible.