High
ECH parsing heap buffer overflow
Type: advisorySources: OSV
Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-3549
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 02:35 UTC · Revision 1
Source evidence
Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.
osv:CVE-2026-3549
Complete source record
{
"id": "339fdf7fdb450e739588313b705cc1cfe6b1bcfe7863acbf37196fed0cb483e9",
"url": "https://osv.dev/vulnerability/CVE-2026-3549",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ECH parsing heap buffer overflow",
"summary": "Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.",
"evidence": "osv:CVE-2026-3549",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-3549",
"aliases": [
"CVE-2026-3549"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/wolfssl/wolfssl",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "922d04b3568c6428a9fb905ddee3ef5a68db3108"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "5.9.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
},
{
"cpe": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "5.9.0"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v5.8.4-stable",
"wolfEntropy2d",
"v5.8.2-stable",
"wolfEntropy1",
"v5.8.0-stable",
"v5.7.6-stable",
"v5.7.4-stable",
"v5.2.1",
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"v5.2.0-stable",
"v5.1.0-stable",
"v5.0.0-stable",
"WCv5.0-RC9",
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"v4.7.1r",
"v4.7.0-stable",
"v4.6.0-stable",
"v4.5.0-stable",
"v4.4.0-stable",
"v4.3.0-stable",
"v4.2.0c",
"v4.2.0-stable",
"v4.1.0-stable",
"v4.0.0-stable",
"list",
"v3.15.7-stable",
"v3.15.6",
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"v3.15.5-stable",
"WCv4-rng-stable",
"v3.15.3-stable",
"l",
"v3.15.0-stable",
"v3.14.4",
"v3.14.2",
"v3.14.0b",
"v3.14.0a",
"v3.14.0-stable",
"v3.13.3",
"v3.13.2",
"v3.13.0-stable",
"v3.12.2-stable",
"v3.12.0-stable",
"v3.11.1-tls13-beta",
"v3.11.0-stable",
"v3.10.3",
"v3.10.2-stable",
"v3.10.0a",
"v3.10.0-stable",
"v3.9.10b",
"v3.9.10-stable",
"v3.9.8",
"v3.9.6w",
"v3.9.6",
"v3.9.1",
"v3.9.0",
"v3.8.0",
"v3.7.3",
"v3.7.1",
"v3.7.0",
"v3.6.9",
"v3.6.8",
"v3.4.6",
"v3.4.2",
"v3.4.0",
"v3.3.3",
"v3.3.0",
"v3.2.6",
"v3.2.4",
"v3.2.0",
"v2.9.4",
"v2.9.2",
"v2.9.1",
"v0.5",
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"v2.8.6",
"v2.8.5a",
"v2.8.5",
"v2.8.4",
"v2.8.3",
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"v2.7.0",
"v2.6.2",
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"v2.4.7",
"v2.4.6",
"v2.4.2",
"v2.0.8",
"v2.0.6",
"v2.0.3",
"v2.0.2",
"v2.0rc3",
"v2.0rc2b",
"v2.0rc2",
"v2.0rc1",
"v1.9.0",
"v1.8.8.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3549.json"
}
}
],
"modified": "2026-10-28T02:30:25.502411986Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3549.json",
"https://nvd.nist.gov/vuln/detail/CVE-2026-3549",
"https://github.com/wolfSSL/wolfssl/pull/9817"
],
"provider_metadata": {
"cwe_ids": [
"CWE-122"
],
"cna_assigner": "wolfSSL",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3549.json"
}
},
"related_cves": [
{
"value": "CVE-2026-3549",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 491949,
"published_at": "2026-03-19T20:09:27.036+00:00"
}