CVE-2021-33560

Published: 08 June 2021

Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. This, for example, affects use of ElGamal in OpenPGP.

Priority

Low

CVSS 3 base score: 7.5

Status

Package Release Status
libgcrypt20
Launchpad, Ubuntu, Debian
Upstream
Released (1.8.7-6)
Ubuntu 21.10 (Impish Indri)
Released (1.8.7-5ubuntu2)
Ubuntu 21.04 (Hirsute Hippo)
Released (1.8.7-2ubuntu2.1)
Ubuntu 20.04 LTS (Focal Fossa)
Released (1.8.5-5ubuntu1.1)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (1.8.1-4ubuntu1.3)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (1.6.5-2ubuntu0.6+esm1)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

Patches:
Upstream: https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=e8b7f10be275bcedb5fc05ed4837a89bfd605c61 (1.9x)

Notes

AuthorNote
mdeslaur
This CVE was originally for the issue that is now CVE=2021-40528
but somehow got switched to the exponent blinding issue instead.
The fix to add exponent blinding appears to only have been added
to 1.9.x but never backported to 1.8.x, contrary to the CVE
description
The commit below was never backported to 1.8.x because the
upstream developers consider this hardening and not a security
issue.

References

Bugs