CVE-2021-40528

MediumCVSS 5.9/10Last modified Jun 17, 2026

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.

Metrics

CVSS 3.1 5.9/10CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Weakness enumeration

CWE-327

Affected software

Vendor	Product	Versions
n/a	n/a	n/a

References

https://eprint.iacr.org/2021/923Technical Description, Third Party Advisory
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1Third Party Advisory
https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2Exploit, Third Party Advisory
https://security.gentoo.org/glsa/202210-13Third Party Advisory
https://eprint.iacr.org/2021/923Technical Description, Third Party Advisory
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1Third Party Advisory
https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2Exploit, Third Party Advisory
https://security.gentoo.org/glsa/202210-13Third Party Advisory

Timeline

Published: Sep 6, 2021
Last modified: Jun 17, 2026
NVD status: Modified

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