High
wolfssl — security advisory
wc_Blake2bHmacFinal and wc_Blake2sHmacFinal discard the message when the key length exceeds the block size, producing a MAC that is independent of the input. When the supplied key is longer than the BLAKE2 block size the key-hashing branch reinitialized the running hash state, discarding the accumulated message data, so the resulting MAC depended only on the key and not on the message being authenticated. This bug is specific to the HMAC-BLAKE2 APIs that were added in wolfSSL version 5.9.0.
- Products
- wolfssl
- Affected versions
- 3.10.2+dfsg-2, 3.12.0+dfsg-1, 3.12.2+dfsg-1, 3.13.0+dfsg-1, 3.4.8+dfsg-1, 4.1.0+dfsg-2, 4.2.0+dfsg-1, 4.2.0+dfsg-2, 4.2.0+dfsg-3, 4.3.0+dfsg-2, 4.6.0-3, 5.0.0-1, 5.1.1-1, 5.2.0-1, 5.2.0-2, 5.5.4-2, 5.5.4-2.1, 5.6.4-2, 5.6.6-1.2, 5.6.6-1.3, 5.6.6-1.3build1, 5.7.2-0.1, 5.8.2-1.2, 5.8.4-1, 5.9.1-0.1, 5.9.2-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-8720
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:24 UTC · Revision 1
Source evidence
wc_Blake2bHmacFinal and wc_Blake2sHmacFinal discard the message when the key length exceeds the block size, producing a MAC that is independent of the input. When the supplied key is longer than the BLAKE2 block size the key-hashing branch reinitialized the running hash state, discarding the accumulated message data, so the resulting MAC depended only on the key and not on the message being authenticated. This bug is specific to the HMAC-BLAKE2 APIs that were added in wolfSSL version 5.9.0.
osv:UBUNTU-CVE-2026-8720
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
wolfssl
Fixed versions: Not specified
Complete source record
{
"id": "f903c116c9bf427fbabad54c686e7354a5601ebde0e7b5f4b7657c45cd2b9858",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-8720",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-8720",
"summary": "wc_Blake2bHmacFinal and wc_Blake2sHmacFinal discard the message when the key length exceeds the block size, producing a MAC that is independent of the input. When the supplied key is longer than the BLAKE2 block size the key-hashing branch reinitialized the running hash state, discarding the accumulated message data, so the resulting MAC depended only on the key and not on the message being authenticated. This bug is specific to the HMAC-BLAKE2 APIs that were added in wolfSSL version 5.9.0.",
"evidence": "osv:UBUNTU-CVE-2026-8720",
"products": [
{
"name": {
"value": "wolfssl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.8+dfsg-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.10.2+dfsg-2",
"evidence": "/affected/1/versions"
},
{
"value": "3.12.0+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.12.2+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.13.0+dfsg-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "4.1.0+dfsg-2",
"evidence": "/affected/2/versions"
},
{
"value": "4.2.0+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "4.2.0+dfsg-2",
"evidence": "/affected/2/versions"
},
{
"value": "4.2.0+dfsg-3",
"evidence": "/affected/2/versions"
},
{
"value": "4.3.0+dfsg-2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "wolfssl",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.6.0-3",
"evidence": "/affected/3/versions"
},
{
"value": "5.0.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "5.1.1-1",
"evidence": "/affected/3/versions"
},
{
"value": "5.2.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "5.2.0-2",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "wolfssl",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.5.4-2",
"evidence": "/affected/4/versions"
},
{
"value": "5.5.4-2.1",
"evidence": "/affected/4/versions"
},
{
"value": "5.6.4-2",
"evidence": "/affected/4/versions"
},
{
"value": "5.6.6-1.2",
"evidence": "/affected/4/versions"
},
{
"value": "5.6.6-1.3",
"evidence": "/affected/4/versions"
},
{
"value": "5.6.6-1.3build1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "wolfssl",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.7.2-0.1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "wolfssl",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.9.1-0.1",
"evidence": "/affected/6/versions"
},
{
"value": "5.9.2-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "wolfssl",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.7.2-0.1",
"evidence": "/affected/7/versions"
},
{
"value": "5.8.2-1.2",
"evidence": "/affected/7/versions"
},
{
"value": "5.8.4-1",
"evidence": "/affected/7/versions"
},
{
"value": "5.9.1-0.1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-8720",
"aliases": [
"UBUNTU-CVE-2026-8720"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"3.4.8+dfsg-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libcyassl5",
"binary_version": "3.4.8+dfsg-1"
},
{
"binary_name": "libwolfssl0",
"binary_version": "3.4.8+dfsg-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"3.10.2+dfsg-2",
"3.12.0+dfsg-1",
"3.12.2+dfsg-1",
"3.13.0+dfsg-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl15",
"binary_version": "3.13.0+dfsg-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"4.1.0+dfsg-2",
"4.2.0+dfsg-1",
"4.2.0+dfsg-2",
"4.2.0+dfsg-3",
"4.3.0+dfsg-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl24",
"binary_version": "4.3.0+dfsg-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"4.6.0-3",
"5.0.0-1",
"5.1.1-1",
"5.2.0-1",
"5.2.0-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl32",
"binary_version": "5.2.0-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"5.5.4-2",
"5.5.4-2.1",
"5.6.4-2",
"5.6.6-1.2",
"5.6.6-1.3",
"5.6.6-1.3build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl42t64",
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}
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},
{
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"ecosystem": "Ubuntu:25.10"
},
"versions": [
"5.7.2-0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl42t64",
"binary_version": "5.7.2-0.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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],
"package": {
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"ecosystem": "Ubuntu:26.10"
},
"versions": [
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"5.9.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl45",
"binary_version": "5.9.2-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "wolfssl",
"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"5.7.2-0.1",
"5.8.2-1.2",
"5.8.4-1",
"5.9.1-0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-8720.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl44",
"binary_version": "5.9.1-0.1"
}
]
}
}
],
"modified": "2026-10-17T13:01:14.183363823Z",
"provider": "osv",
"upstream": [
"CVE-2026-8720"
],
"references": [
"https://ubuntu.com/security/CVE-2026-8720",
"https://www.cve.org/CVERecord?id=CVE-2026-8720",
"https://github.com/wolfSSL/wolfssl/pull/10447",
"https://www.wolfssl.com/docs/security-vulnerabilities/"
]
},
"related_cves": [
{
"value": "CVE-2026-8720",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 361334,
"published_at": "2026-06-25T22:17:00+00:00"
}