High
Security advisory
An issue was discovered in fastecdsa before 2.1.2. When using the NIST P-256 curve in the ECDSA implementation, the point at infinity is mishandled. This means that for an extreme value in k and s^-1, the signature verification fails even if the signature is correct. This behavior is not solely a usability problem. There are some threat models where an attacker can benefit by successfully guessing users for whom signature verification will fail.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2020-12607
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 12:33 UTC · Revision 1
Source evidence
An issue was discovered in fastecdsa before 2.1.2. When using the NIST P-256 curve in the ECDSA implementation, the point at infinity is mishandled. This means that for an extreme value in k and s^-1, the signature verification fails even if the signature is correct. This behavior is not solely a usability problem. There are some threat models where an attacker can benefit by successfully guessing users for whom signature verification will fail.
osv:CVE-2020-12607
Complete source record
{
"id": "6ce9a9956b9c4ee501b220e35bfefca6985a07f829e45b4131e123af22c60f55",
"url": "https://osv.dev/vulnerability/CVE-2020-12607",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2020-12607",
"summary": "An issue was discovered in fastecdsa before 2.1.2. When using the NIST P-256 curve in the ECDSA implementation, the point at infinity is mishandled. This means that for an extreme value in k and s^-1, the signature verification fails even if the signature is correct. This behavior is not solely a usability problem. There are some threat models where an attacker can benefit by successfully guessing users for whom signature verification will fail.",
"evidence": "osv:CVE-2020-12607",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2020-12607",
"aliases": [
"CVE-2020-12607",
"GHSA-56wv-2wr9-3h9r",
"PYSEC-2020-42"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/antonkueltz/fastecdsa",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "7b64e3efaa806b4daaf73bb5172af3581812f8de"
},
{
"fixed": "4a16daeaf139be20654ef58a9fe4c79dc030458c"
},
{
"fixed": "e592f106edd5acf6dacedfab2ad16fe6c735c9d1"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:antonkueltz:fastecdsa:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "2.1.2"
}
],
"source": "CPE_RANGE"
},
{
"range": [
{
"fixed": "4a16daeaf139be20654ef58a9fe4c79dc030458c"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "7b64e3efaa806b4daaf73bb5172af3581812f8de"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "e592f106edd5acf6dacedfab2ad16fe6c735c9d1"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"v2.1.1",
"v2.1.0",
"v2.0.0",
"v1.7.5",
"v1.7.4",
"v1.7.3",
"v1.7.2",
"v1.7.1",
"v1.6.5",
"v1.6.4",
"v1.6.3",
"v1.6.2",
"v1.2.1",
"v1.1.3",
"v1.0.3",
"v1.0.2",
"v1.0.1"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-12607.json",
"vanir_signatures": [
{
"id": "CVE-2020-12607-66ce0194",
"digest": {
"length": 830,
"function_hash": "93520763919975657384232032081005663602"
},
"source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1",
"target": {
"file": "src/curveMath.c",
"function": "pointZZ_pDouble"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2020-12607-765a86e6",
"digest": {
"length": 1007,
"function_hash": "114807553560984464700912165694170755712"
},
"source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1",
"target": {
"file": "src/curveMath.c",
"function": "pointZZ_pMul"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2020-12607-9ebef2d1",
"digest": {
"length": 794,
"function_hash": "237713034721248222028732838030589999764"
},
"source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1",
"target": {
"file": "src/curveMath.c",
"function": "pointZZ_pAdd"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2020-12607-adb032bc",
"digest": {
"threshold": 0.9,
"line_hashes": [
"295440111576572506065665976290646547187",
"196854035119909962313773951870531590818",
"317871309843992884374969037078204491522",
"104375746076562032098332227659040301528",
"65416599458374717787017732325794096570",
"177423792026663125093054846541122329542",
"218619352812740939546316886251052461695",
"40930251885493100673819922373020214212",
"243540426651314462511606196020035304659",
"273798193599705150604646108665496793181",
"170054887755278315323162088544007563571",
"197353946011006447932649302589988372905",
"234408837222518631626031317531483544714",
"74221276442437195587473428445690813998"
]
},
"source": "https://github.com/antonkueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1",
"target": {
"file": "src/curveMath.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-20T13:51:14Z"
}
}
],
"modified": "2026-10-20T13:51:14.910686534Z",
"provider": "osv",
"references": [
"https://github.com/AntonKueltz/fastecdsa/commit/4a16daeaf139be20654ef58a9fe4c79dc030458c",
"https://github.com/AntonKueltz/fastecdsa/commit/7b64e3efaa806b4daaf73bb5172af3581812f8de",
"https://github.com/AntonKueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1",
"https://github.com/AntonKueltz/fastecdsa/issues/52"
],
"provider_metadata": {}
},
"related_cves": [
{
"value": "CVE-2020-12607",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 388277,
"published_at": "2020-06-02T21:15:10.607+00:00"
}