Medium
libeddsa-java, ruby-ed25519 — security advisory
The implementation of EdDSA in EdDSA-Java (aka ed25519-java) through 0.3.0 exhibits signature malleability and does not satisfy the SUF-CMA (Strong Existential Unforgeability under Chosen Message Attacks) property. This allows attackers to create new valid signatures different from previous signatures for a known message.
- Products
- libeddsa-java, ruby-ed25519
- Affected versions
- 0.3.0-2, 0.3.0-2.1, 0.3.0-3, 1.2.4-1, 1.2.4-1build1, 1.2.4-2, 1.2.4-2build1, 1.3.0+ds-1, 1.3.0+ds-1build2, 1.3.0+ds-1build3, 1.3.0+ds-1build4, 1.3.0+ds-1build5, 1.4.0+ds-1
- Fixed versions
- Not specified
- CVEs
- CVE-2020-36843
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 00:52 UTC · Revision 1
Source evidence
The implementation of EdDSA in EdDSA-Java (aka ed25519-java) through 0.3.0 exhibits signature malleability and does not satisfy the SUF-CMA (Strong Existential Unforgeability under Chosen Message Attacks) property. This allows attackers to create new valid signatures different from previous signatures for a known message.
osv:UBUNTU-CVE-2020-36843
ruby-ed25519
Fixed versions: Not specified
ruby-ed25519
Fixed versions: Not specified
ruby-ed25519
Fixed versions: Not specified
libeddsa-java
Fixed versions: Not specified
ruby-ed25519
Fixed versions: Not specified
libeddsa-java
Fixed versions: Not specified
ruby-ed25519
Fixed versions: Not specified
libeddsa-java
Fixed versions: Not specified
ruby-ed25519
Fixed versions: Not specified
Complete source record
{
"id": "7a295bb4a9fe7eaae7a06d8fa3aecefa6632ce569ee3c9a27a8976a85c2f42d3",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2020-36843",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2020-36843",
"summary": "The implementation of EdDSA in EdDSA-Java (aka ed25519-java) through 0.3.0 exhibits signature malleability and does not satisfy the SUF-CMA (Strong Existential Unforgeability under Chosen Message Attacks) property. This allows attackers to create new valid signatures different from previous signatures for a known message.",
"evidence": "osv:UBUNTU-CVE-2020-36843",
"products": [
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.2.4-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.2.4-1build1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.2.4-2",
"evidence": "/affected/1/versions"
},
{
"value": "1.2.4-2build1",
"evidence": "/affected/1/versions"
},
{
"value": "1.3.0+ds-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.3.0+ds-1build2",
"evidence": "/affected/2/versions"
},
{
"value": "1.3.0+ds-1build3",
"evidence": "/affected/2/versions"
},
{
"value": "1.3.0+ds-1build4",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "libeddsa-java",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.3.0-2",
"evidence": "/affected/3/versions"
},
{
"value": "0.3.0-2.1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.3.0+ds-1build5",
"evidence": "/affected/4/versions"
},
{
"value": "1.4.0+ds-1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "libeddsa-java",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.3.0-3",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.4.0+ds-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "libeddsa-java",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.3.0-2.1",
"evidence": "/affected/7/versions"
},
{
"value": "0.3.0-3",
"evidence": "/affected/7/versions"
}
]
},
{
"name": {
"value": "ruby-ed25519",
"evidence": "/affected/8/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.4.0+ds-1",
"evidence": "/affected/8/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2020-36843",
"aliases": [
"UBUNTU-CVE-2020-36843"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "ruby-ed25519",
"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"1.2.4-1",
"1.2.4-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-ed25519",
"binary_version": "1.2.4-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "ruby-ed25519",
"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.2.4-2",
"1.2.4-2build1",
"1.3.0+ds-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-ed25519",
"binary_version": "1.3.0+ds-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "ruby-ed25519",
"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"1.3.0+ds-1build2",
"1.3.0+ds-1build3",
"1.3.0+ds-1build4"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-ed25519",
"binary_version": "1.3.0+ds-1build4"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libeddsa-java",
"purl": "pkg:deb/ubuntu/libeddsa-java?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"0.3.0-2",
"0.3.0-2.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libeddsa-java",
"binary_version": "0.3.0-2.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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"package": {
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"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.3.0+ds-1build5",
"1.4.0+ds-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-ed25519",
"binary_version": "1.4.0+ds-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "libeddsa-java",
"purl": "pkg:deb/ubuntu/libeddsa-java?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"0.3.0-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
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{
"binary_name": "libeddsa-java",
"binary_version": "0.3.0-3"
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},
{
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"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.4.0+ds-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
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},
{
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"purl": "pkg:deb/ubuntu/libeddsa-java?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
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"0.3.0-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libeddsa-java",
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}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/ruby-ed25519?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.4.0+ds-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-36843.json"
},
"ecosystem_specific": {
"binaries": [
{
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}
]
}
}
],
"modified": "2026-10-17T12:56:14.761718668Z",
"provider": "osv",
"upstream": [
"CVE-2020-36843"
],
"references": [
"https://ubuntu.com/security/CVE-2020-36843",
"https://www.cve.org/CVERecord?id=CVE-2020-36843",
"https://eprint.iacr.org/2020/1244",
"https://github.com/str4d/ed25519-java/issues/82#issue-727629226"
]
},
"related_cves": [
{
"value": "CVE-2020-36843",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 355022,
"published_at": "2025-03-13T06:15:00+00:00"
}