CVSS 3.1
5.9 mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:NCVE-2021-40529
Medium (5.9). EPSS 1.5% chance of exploitation in the next 30 days.
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.
Severity
- EPSS
- 1.5% chance of exploitation in the next 30 days; higher than 74% of CVEs (scores of 2026-10-31)
- CWE
- CWE-327
- Published
- Modified
- Record from
- the NVD, synced
Affected
- botan_project:botan
- fedoraproject:fedora
- mozilla:thunderbird
References
- https://eprint.iacr.org/2021/923
- https://github.com/randombit/botan/pull/2790
- https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
- https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72NB4OLD3VHJC3YF3PEP2HKF6BYURPAO/