Description
An issue was discovered in Enigmail before 1.9.9. In a variant of CVE-2017-17847, signature spoofing is possible for multipart/related messages because a signed message part can be referenced with a cid: URI but not actually displayed. In other words, the entire containing message appears to be signed, but the recipient does not see any of the signed text.
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 11 | enigmail | 2:1.9.9-1 | — |
| Debian 9 | enigmail | 2:1.9.9-1~deb9u1 | DSA-4070-1 |
| Debian 8 | enigmail | 2:1.9.9-1~deb8u1 | DSA-4070-1 |
| Debian 7 | enigmail | 2:1.9.9-1~deb7u1 | DLA-1219-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | enigmail | 2:1.9.9-0ubuntu0.16.04.1 | — |
| Ubuntu 14.04 LTS | enigmail | 2:1.9.9-0ubuntu0.14.04.1 | — |
Advisories 2
- DSA-4070-1 enigmail - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1219-1 enigmail - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- https://sourceforge.net/p/enigmail/bugs/709/
- https://lists.debian.org/debian-security-announce/2017/msg00333.html
- [debian-lts-announce] 20171223 [SECURITY] [DLA 1219-1] enigmail security update mailing-list
- DSA-4070 vendor-advisory
- [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
- https://github.com/RUB-NDS/Johnny-You-Are-Fired
- https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf