CVE-2021-40529

MEDIUM

Botan < 2.18.1 - Plaintext Recovery via ElGamal Cross-Configuration Attack

Title source: llm

Description

The ElGamal implementation in Botan through 2.18.1, as used in Thunderbird and other products, 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.

References (7)

Core 7

Core References

Technical Description, Third Party Advisory x_refsource_misc

https://eprint.iacr.org/2021/923

Third Party Advisory x_refsource_misc

https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1

Exploit, Third Party Advisory x_refsource_misc

https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2

Patch, Third Party Advisory x_refsource_misc

https://github.com/randombit/botan/pull/2790

Mailing List, Third Party Advisory vendor-advisory x_refsource_fedora

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UPHGYWNJQKWLTUWBNSFB4F66MQDIL3IB/

Mailing List, Third Party Advisory vendor-advisory x_refsource_fedora

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72NB4OLD3VHJC3YF3PEP2HKF6BYURPAO/

Third Party Advisory vendor-advisory x_refsource_gentoo

https://security.gentoo.org/glsa/202208-14

Scores

CVSS v3 5.9

EPSS 0.0030

EPSS Percentile 53.4%

Attack Vector NETWORK

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

Details

CWE

CWE-327

Status published

Products (4)

botan_project/botan < 2.18.1

fedoraproject/fedora 34

fedoraproject/fedora 35

mozilla/thunderbird < 91.12.0

Published Sep 06, 2021

Tracked Since Feb 18, 2026