Medium
Security advisory
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-40529
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 11:54 UTC · Revision 1
Source evidence
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.
osv:CVE-2021-40529
Complete source record
{
"id": "50ac0e62dc850b93c44ccd39dc341231ba73a3a1225bd5be581179a283bb7667",
"url": "https://osv.dev/vulnerability/CVE-2021-40529",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-40529",
"summary": "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.",
"evidence": "osv:CVE-2021-40529",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2021-40529",
"aliases": [
"CVE-2021-40529"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/randombit/botan",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"last_affected": "d4bd416702a65eddcc14ee06b9c1b674631e6ae3"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"last_affected": "2.18.1"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"2.18.1",
"2.18.0",
"2.17.3",
"2.17.2",
"2.17.1",
"2.17.0",
"2.16.0",
"2.15.0",
"2.14.0",
"2.13.0",
"2.12.1",
"2.12.0",
"2.11.0",
"2.10.0",
"2.9.0",
"2.8.0",
"2.7.0",
"2.6.0",
"2.5.0",
"2.4.0",
"2.3.0",
"2.2.0",
"2.1.0",
"2.0.1",
"2.0.0",
"1.11.34",
"1.11.33",
"1.11.32",
"1.11.31",
"1.11.30",
"1.11.29",
"1.11.28",
"1.11.27",
"1.11.26",
"1.11.25",
"1.11.24",
"1.11.23",
"1.11.22",
"1.11.21",
"1.11.20",
"1.11.19",
"1.11.18",
"1.11.17",
"1.11.16",
"1.11.15",
"1.11.14",
"1.11.13",
"1.11.12",
"1.11.11",
"1.11.10",
"1.11.9",
"1.11.8",
"1.11.7",
"1.11.6",
"1.11.5",
"1.11.3",
"1.11.2",
"1.11.0",
"1.10.1",
"1.10.0",
"1.9.18",
"1.9.17",
"1.9.16",
"1.9.15",
"1.10.0-rc1",
"1.9.14",
"1.9.13",
"1.9.12",
"1.9.11",
"1.9.10",
"1.9.9",
"1.9.8",
"1.9.7",
"1.9.6",
"1.9.5",
"1.9.4",
"1.9.3",
"1.8.8",
"1.8.7",
"1.8.6",
"1.8.5",
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"1.8.3",
"1.8.2",
"1.7.24",
"1.7.23",
"1.7.22",
"1.7.21",
"1.7.20",
"1.7.19",
"1.7.18",
"1.7.17",
"1.7.16",
"1.7.15",
"1.7.11",
"1.7.10",
"1.7.9",
"1.7.8",
"1.7.7",
"1.7.6",
"1.7.5",
"1.7.4",
"1.7.3",
"1.7.1",
"1.7.0",
"1.6.1",
"1.6.0",
"1.5.13",
"1.5.12",
"1.5.11",
"1.5.10",
"1.5.9",
"1.5.8",
"1.5.7",
"1.5.6"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-40529.json"
}
}
],
"modified": "2026-10-20T10:54:56.123111972Z",
"provider": "osv",
"references": [
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72NB4OLD3VHJC3YF3PEP2HKF6BYURPAO/",
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UPHGYWNJQKWLTUWBNSFB4F66MQDIL3IB/",
"https://eprint.iacr.org/2021/923",
"https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1",
"https://security.gentoo.org/glsa/202208-14",
"https://github.com/randombit/botan/pull/2790",
"https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*"
],
"vendor_product": "mozilla:thunderbird",
"extracted_events": [
{
"range": [
{
"fixed": "91.12.0"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*",
"cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*"
],
"vendor_product": "fedoraproject:fedora",
"extracted_events": [
{
"range": [
{
"introduced": "34"
},
{
"last_affected": "34"
},
{
"introduced": "35"
},
{
"last_affected": "35"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-40529",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 386487,
"published_at": "2021-09-06T19:15:07.63+00:00"
}