{"id":"CVE-2020-12607","aliases":["EUVD-2020-0078","GHSA-56wv-2wr9-3h9r","PYSEC-2020-42"],"status":"published","title":"Improper Verification of Cryptographic Signature in fastecdsa","description":"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.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.01311,"percentile":0.70899,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-347"],"published":"2020-06-02T21:00:52Z","modified":"2026-10-20T13:51:14Z","fixes":[{"ecosystem":"PyPI","package":"fastecdsa","fixed_in":["2.1.2"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"fastecdsa","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.2"}]}]},{"source":"osv","ecosystem":"PyPI","package":"fastecdsa","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.2"}]}],"versions":["1.0.0b1","1.0.1","1.0.1b1","1.0.1b2","1.0.1b3","1.0.2","1.0.3","1.1.0","1.1.1","1.1.2","1.1.3","1.2.1","1.3.1","1.3.2","1.4.1","1.4.2","1.4.3","1.5.1","1.5.2","1.6.1","1.6.2","1.6.3","1.6.4","1.6.5","1.7.0","1.7.1","1.7.2","1.7.3","1.7.4","1.7.5","2.0.0","2.1.0","2.1.1"]},{"source":"osv","ecosystem":"PyPI","package":"fastecdsa","ranges":[{"type":"GIT","events":[{"introduced":"0"},{"fixed":"4a16daeaf139be20654ef58a9fe4c79dc030458c"},{"fixed":"7b64e3efaa806b4daaf73bb5172af3581812f8de"},{"fixed":"e592f106edd5acf6dacedfab2ad16fe6c735c9d1"}]},{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.2"}]}],"versions":["1.0.0b1","1.0.1b1","1.0.1b2","1.0.1b3","1.0.1","1.0.2","1.0.3","1.1.0","1.1.1","1.1.2","1.1.3","1.2.1","1.3.1","1.3.2","1.4.1","1.4.2","1.4.3","1.5.1","1.5.2","1.6.1","1.6.2","1.6.3","1.6.4","1.6.5","1.7.0","1.7.1","1.7.2","1.7.3","1.7.4","1.7.5","2.0.0","2.1.0","2.1.1"]}],"products":[{"vendor":"antonkueltz","product":"fastecdsa"}],"references":[{"url":"https://github.com/AntonKueltz/fastecdsa/commit/4a16daeaf139be20654ef58a9fe4c79dc030458c","tags":["x_refsource_CONFIRM","x_transferred","Issue Tracking","Patch","Third Party Advisory","fix","web"]},{"url":"https://github.com/AntonKueltz/fastecdsa/issues/52","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Third Party Advisory","evidence","web","report"]},{"url":"https://github.com/AntonKueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1","tags":["x_refsource_CONFIRM","x_transferred","Patch","Third Party Advisory","fix","web"]},{"url":"https://github.com/AntonKueltz/fastecdsa/commit/7b64e3efaa806b4daaf73bb5172af3581812f8de","tags":["x_refsource_CONFIRM","x_transferred","Patch","Third Party Advisory","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-12607","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-56wv-2wr9-3h9r","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/fastecdsa/PYSEC-2020-42.yaml","tags":["web"]},{"url":"https://github.com/AntonKueltz/fastecdsa","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2020-12607","description":"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.","status":"published","published":"2020-06-02T21:00:52Z","modified":"2024-08-04T12:04:21.646Z","updated_at":"2026-11-02T14:35:53.236501Z"}],"euvd":[{"id":"EUVD-2020-0078","description":"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.","status":"published","published":"2020-06-02T21:00:52Z","modified":"2024-08-04T12:04:21Z","updated_at":"2026-11-03T03:07:39.896975Z"}],"ghsa":[{"id":"GHSA-56wv-2wr9-3h9r","title":"Improper Verification of Cryptographic Signature in fastecdsa","description":"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\u003csup\u003e-1\u003c/sup\u003e, 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.","status":"published","published":"2021-10-12T16:30:37Z","modified":"2024-09-20T17:12:17Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","level":"high"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T14:38:04.690827Z"}],"nvd":[{"id":"CVE-2020-12607","description":"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.","status":"published","published":"2020-06-02T21:15:10.607Z","modified":"2026-06-17T02:52:00.79Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:P/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T14:06:04.922138Z"}],"osv":[{"id":"CVE-2020-12607","description":"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.","status":"published","published":"2020-06-02T21:15:10.607Z","modified":"2026-10-20T13:51:14.910686534Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-02T15:44:14.034736Z"},{"id":"GHSA-56wv-2wr9-3h9r","title":"Improper Verification of Cryptographic Signature in fastecdsa","description":"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\u003csup\u003e-1\u003c/sup\u003e, 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.","status":"published","published":"2021-10-12T16:30:37Z","modified":"2025-02-12T18:54:35.292885Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"high"},{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T15:46:37.864461Z"},{"id":"PYSEC-2020-42","description":"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.","status":"published","published":"2020-06-02T21:15:00Z","modified":"2023-11-08T04:02:10.552763Z","updated_at":"2026-11-02T15:52:52.682031Z"}]}}