Vulnerability · Published Dec 22, 2022 · Assigned by mozilla
CVE-2021-4126
Medium 6.5
In plain English
A medium-severity security flaw in Thunderbird from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
When receiving an OpenPGP/MIME signed email message that contains an additional outer MIME message layer, for example a message footer added by a mailing list gateway, Thunderbird only considered the inner signed message for the signature validity. This gave the false impression that the additional contents were also covered by the digital signature. Starting with Thunderbird version 91.4.1, only the signature that belongs to the top level MIME part will be considered for the displayed status. This vulnerability affects Thunderbird < 91.4.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | thunderbird | 91.4.1-r0 | ALPINE-CVE-2021-4126 |
| Alpine:v3.21 | thunderbird | 91.4.1-r0 | ALPINE-CVE-2021-4126 |
| Alpine:v3.22 | thunderbird | 91.4.1-r0 | ALPINE-CVE-2021-4126 |
| Alpine:v3.23 | thunderbird | 91.4.1-r0 | ALPINE-CVE-2021-4126 |
| Debian:12 | thunderbird | 1:91.4.1-1 | DEBIAN-CVE-2021-4126 |
| Debian:13 | thunderbird | 1:91.4.1-1 | DEBIAN-CVE-2021-4126 |
| Debian:14 | thunderbird | 1:91.4.1-1 | DEBIAN-CVE-2021-4126 |
| Ubuntu:22.04:LTS | thunderbird | 1:91.5.0+build1-0ubuntu1 | UBUNTU-CVE-2021-4126 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | unspecified – before 91.4.1 |