CVE-2021-40528

NameCVE-2021-40528
DescriptionThe 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2691-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
libgcrypt20 (PTS)buster1.8.4-5+deb10u1fixed
bullseye1.8.7-6fixed
bookworm, sid1.10.1-2fixed

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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