CVE-2021-33560

NameCVE-2021-33560
DescriptionLibgcrypt 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-2691-1
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
libgcrypt20 (PTS)stretch1.7.6-2+deb9u3vulnerable
stretch (security)1.7.6-2+deb9u4fixed
buster1.8.4-5+deb10u1fixed
bullseye1.8.7-6fixed
bookworm, sid1.9.4-3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
libgcrypt20sourcestretch1.7.6-2+deb9u4DLA-2691-1
libgcrypt20sourcebuster1.8.4-5+deb10u1
libgcrypt20source(unstable)1.8.7-6

Notes

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.

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