Medium severity5.9NVD Advisory· Published Sep 6, 2021· Updated Jun 17, 2026
CVE-2021-40529
CVE-2021-40529
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
12cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:*range: <=2.18.1
- (no CPE)range: <=2.18.1
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
- Botan/Botandescription
- osv-coords6 versionspkg:rpm/opensuse/Botan&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Leap%2015.2pkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Leap%2015.3pkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Tumbleweedpkg:rpm/suse/MozillaThunderbird&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2015%20SP2pkg:rpm/suse/MozillaThunderbird&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2015%20SP3
< 2.18.2-1.1+ 5 more
- (no CPE)range: < 2.18.2-1.1
- (no CPE)range: < 91.4.0-lp152.2.52.1
- (no CPE)range: < 91.4.0-8.45.2
- (no CPE)range: < 91.4.0-1.1
- (no CPE)range: < 91.4.0-8.45.2
- (no CPE)range: < 91.4.0-8.45.2
Patches
Vulnerability mechanics
References
7- github.com/randombit/botan/pull/2790nvdPatchThird Party Advisory
- ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2nvdExploitThird Party Advisory
- eprint.iacr.org/2021/923nvdTechnical DescriptionThird Party Advisory
- ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1nvdThird Party Advisory
- security.gentoo.org/glsa/202208-14nvdThird Party Advisory
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72NB4OLD3VHJC3YF3PEP2HKF6BYURPAO/nvd
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UPHGYWNJQKWLTUWBNSFB4F66MQDIL3IB/nvd
News mentions
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