Critical
wolfssl — security advisory
Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.
- 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-2026-5187
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:28 UTC · Revision 1
Source evidence
Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.
osv:UBUNTU-CVE-2026-5187
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": "2490d626658aeb059c899204de9b4e5351bc8e741c38059b9575abb7653dd154",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-5187",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-5187",
"summary": "Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.",
"evidence": "osv:UBUNTU-CVE-2026-5187",
"products": [
{
"name": {
"value": "wolfssl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.8+dfsg-1",
"evidence": "/affected/0/versions"
}
]
},
{
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"evidence": "/affected/1/package/name"
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
},
{
"value": "3.12.2+dfsg-1",
"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
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{
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{
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{
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"evidence": "/affected/2/versions"
},
{
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"evidence": "/affected/2/versions"
},
{
"value": "4.2.0+dfsg-3",
"evidence": "/affected/2/versions"
},
{
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"evidence": "/affected/2/versions"
}
]
},
{
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"evidence": "/affected/3/package/name"
},
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"affected_versions": [
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"evidence": "/affected/3/versions"
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{
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"evidence": "/affected/3/versions"
},
{
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"evidence": "/affected/3/versions"
},
{
"value": "5.2.0-1",
"evidence": "/affected/3/versions"
},
{
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"evidence": "/affected/3/versions"
}
]
},
{
"name": {
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"evidence": "/affected/4/package/name"
},
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"affected_versions": [
{
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"evidence": "/affected/4/versions"
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{
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"evidence": "/affected/4/versions"
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{
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},
{
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"evidence": "/affected/4/versions"
},
{
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"evidence": "/affected/4/versions"
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{
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{
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},
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"evidence": "/affected/5/versions"
}
]
},
{
"name": {
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"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"
}
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},
{
"name": {
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"evidence": "/affected/7/package/name"
},
"prerequisites": [],
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"affected_versions": [
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"evidence": "/affected/7/versions"
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{
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"evidence": "/affected/7/versions"
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{
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"evidence": "/affected/7/versions"
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{
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],
"severity": "critical",
"structured": {
"id": "UBUNTU-CVE-2026-5187",
"aliases": [
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],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
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],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5187.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": [
{
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}
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}
],
"package": {
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"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
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"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-2026-5187.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libwolfssl15",
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}
]
}
},
{
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],
"package": {
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"purl": "pkg:deb/ubuntu/wolfssl?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
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"4.2.0+dfsg-1",
"4.2.0+dfsg-2",
"4.2.0+dfsg-3",
"4.3.0+dfsg-2"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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},
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"5.0.0-1",
"5.1.1-1",
"5.2.0-1",
"5.2.0-2"
],
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},
"ecosystem_specific": {
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},
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"5.5.4-2.1",
"5.6.4-2",
"5.6.6-1.2",
"5.6.6-1.3",
"5.6.6-1.3build1"
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},
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}
],
"modified": "2026-10-17T12:58:34.513810472Z",
"provider": "osv",
"upstream": [
"CVE-2026-5187"
],
"references": [
"https://ubuntu.com/security/CVE-2026-5187",
"https://www.cve.org/CVERecord?id=CVE-2026-5187",
"https://github.com/wolfSSL/wolfssl/pull/10025",
"https://github.com/wolfSSL/wolfssl"
]
},
"related_cves": [
{
"value": "CVE-2026-5187",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 358807,
"published_at": "2026-04-09T20:16:00+00:00"
}