| Name | CVE-2021-40528 |
| Description | The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-2691-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| libgcrypt20 (PTS) | buster | 1.8.4-5+deb10u1 | fixed |
| bullseye | 1.8.7-6 | fixed | |
| bookworm | 1.10.1-3 | fixed | |
| sid, trixie | 1.10.3-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| libgcrypt20 | source | stretch | 1.7.6-2+deb9u4 | DLA-2691-1 | ||
| libgcrypt20 | source | buster | 1.8.4-5+deb10u1 | |||
| libgcrypt20 | source | (unstable) | 1.8.7-6 |
https://dev.gnupg.org/T5328
https://eprint.iacr.org/2021/923.pdf
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=3462280f2e23e16adf3ed5176e0f2413d8861320 (1.9.x)
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=707c3c5c511ee70ad0e39ec613471f665305fbea (1.8.x)
See notes on CVE-2021-40528 on the confusion about swapping of scope of
CVE-2021-40528 and CVE-2021-33560.