| Name | CVE-2018-6829 |
| Description | cipher/elgamal.c in Libgcrypt through 1.8.2, when used to encrypt messages directly, improperly encodes plaintexts, which allows attackers to obtain sensitive information by reading ciphertext data (i.e., it does not have semantic security in face of a ciphertext-only attack). The Decisional Diffie-Hellman (DDH) assumption does not hold for Libgcrypt's ElGamal implementation. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| gnupg (PTS) | jessie, jessie (lts) | 1.4.18-7+deb8u5 | vulnerable |
| gnupg1 (PTS) | stretch (security), stretch (lts), stretch | 1.4.21-4+deb9u1 | vulnerable |
| buster | 1.4.23-1 | vulnerable |
| trixie, bullseye, bookworm | 1.4.23-1.1 | vulnerable |
| sid | 1.4.23-2 | vulnerable |
| libgcrypt20 (PTS) | jessie, jessie (lts) | 1.6.3-2+deb8u9 | vulnerable |
| stretch (security), stretch (lts), stretch | 1.7.6-2+deb9u4 | vulnerable |
| buster | 1.8.4-5+deb10u1 | vulnerable |
| bullseye | 1.8.7-6 | vulnerable |
| bookworm | 1.10.1-3 | vulnerable |
| sid, trixie | 1.10.3-2 | vulnerable |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| gnupg | source | (unstable) | (unfixed) | unimportant | | |
| gnupg1 | source | (unstable) | (unfixed) | unimportant | | |
| libgcrypt11 | source | (unstable) | (unfixed) | unimportant | | |
| libgcrypt20 | source | (unstable) | (unfixed) | unimportant | | |
Notes
https://github.com/weikengchen/attack-on-libgcrypt-elgamal
https://github.com/weikengchen/attack-on-libgcrypt-elgamal/wiki
https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004394.html
GnuPG uses ElGamal in hybrid mode only.
This is not a vulnerability in libgcrypt, but in an application using
it in an insecure manner, see also
https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004401.html