Description
A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content. This vulnerability affects Thunderbird < 60.5.1.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | unspecified – < 60.5.1 | 60.5.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | thunderbird | 1:60.5.1-1 | — |
| Debian 13 | thunderbird | 1:60.5.1-1 | — |
| Debian 12 | thunderbird | 1:60.5.1-1 | — |
| Debian 9 | thunderbird | 1:60.5.1-1~deb9u1 | DSA-4392-1 |
| Debian 8 | thunderbird | 1:60.5.1-1~deb8u1 | DLA-1678-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | thunderbird | 1:60.5.1+build2-0ubuntu0.18.04.1 | USN-3897-1 |
| Ubuntu 16.04 LTS | thunderbird | 1:60.5.1+build2-0ubuntu0.16.04.1 | USN-3897-1 |
| Ubuntu 14.04 LTS | thunderbird | 1:60.5.1+build2-0ubuntu0.14.04.1 | USN-3897-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | thunderbird | 60.6.1-1.el8 | RHSA-2019:1144 |
| RHEL 7 | thunderbird | 60.6.1-1.el7_6 | RHSA-2019:0681 |
| RHEL 6 | thunderbird | 60.6.1-1.el6_10 | RHSA-2019:0680 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 | MozillaThunderbird | 60.5.1-3.24.1 | SUSE-SU-2019:0853-1, SUSE-SU-2019:0469-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 12 | MozillaThunderbird | 60.5.1-79.1 | openSUSE-SU-2019:0249-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaThunderbird | 91.1.1-1.1 | openSUSE-SU-2024:10601-1 |
| openSUSE Leap 15.0 | MozillaThunderbird | 60.6.1-lp150.3.37.1 | openSUSE-SU-2019:1162-1 |
Advisories 11
- RHSA-2019:1144 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2019:0680 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2019:0681 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- USN-3897-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-4392-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1678-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2019:0853-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:0469-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:1162-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10601-1 MozillaThunderbird-91.1.1-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- openSUSE-SU-2019:0249-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · May 2, 2025
References
- openSUSE-SU-2019:1162 vendor-advisory
- https://www.mozilla.org/security/advisories/mfsa2019-06/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1507218
- [oss-security] 20190430 Spoofing OpenPGP and S/MIME Signatures in Emails (multiple clients) mailing-list
- 20190430 OpenPGP and S/MIME signature forgery attacks in multiple email clients mailing-list
- http://packetstormsecurity.com/files/152703/Johnny-You-Are-Fired.html
- RHSA-2019:1144 vendor-advisory
- https://github.com/RUB-NDS/Johnny-You-Are-Fired
- https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf