{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-18798",
"assignerOrgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
"state": "PUBLISHED",
"assignerShortName": "openssl",
"dateReserved": "2026-08-04T09:45:25.371Z",
"datePublished": "2026-08-25T12:59:04.715Z",
"dateUpdated": "2026-08-25T14:15:04.879Z"
},
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "OpenSSL",
"vendor": "OpenSSL",
"versions": [
{
"lessThan": "4.0.2",
"status": "affected",
"version": "4.0.0",
"versionType": "semver"
},
{
"lessThan": "3.6.4",
"status": "affected",
"version": "3.6.0",
"versionType": "semver"
},
{
"lessThan": "3.5.8",
"status": "affected",
"version": "3.5.0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "reporter",
"value": "Fuzz0x (ZKSC Institute of Security Research)"
},
{
"lang": "en",
"type": "reporter",
"value": "Emilio Galle"
},
{
"lang": "en",
"type": "reporter",
"value": "Feng Xue (ThreatBoon)"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Alexandr Nedvedicky"
}
],
"datePublic": "2026-08-25T11:36:16.000Z",
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Issue summary: QUIC server may double free QRX (QUIC record layer RX) object
when channel creation fails for initial packet.
Impact summary: Double free leads to heap corruption, which typically results in
termination of QUIC server process, leading to Denial of Service. There is so
far no evidence that this double free is exploitable for remote code execution,
thus it is considered highly improbable.
CWE: CWE-415: Double Free
Description: In order to validate initial packet, OpenSSL QUIC stack default
packet handler (port_default_packet_handler()) creates a so-called QRX object.
If the initial packet validates successfully with QRX object, the default packet
handler proceeds to channel (connection object) creation. The QRX object used
for packet validation is passed to port_bind_channel(), so it becomes part of
the newly created connection. If port_bind_channel() fails, then it also frees
the QRX object. Once port_bind_channel() returns, the port_default_packet_handler()
detects the failure and proceeds to the error branch, where the same QRX object is
freed for the second time.
The failure in port_bind_channel() function can be induced with a relatively
low effort by a malformed (non RFC 9000 compliant) INITIAL packet. If the packet
carries DCID (destination connection ID) which is shorter than 8 bytes, then
port_bind_channel() jumps to the error path after ossl_quic_lcidm_enrol_odcid()
detects that the DCID has invalid length.
FIPS impact: no
The FIPS module is not affected, as the QUIC implementation is outside of
the OpenSSL FIPS module boundary."
}
],
"value": "Issue summary: QUIC server may double free QRX (QUIC record layer RX) object\nwhen channel creation fails for initial packet.\n\nImpact summary: Double free leads to heap corruption, which typically results in \ntermination of QUIC server process, leading to Denial of Service. There is so\nfar no evidence that this double free is exploitable for remote code execution,\nthus it is considered highly improbable.\n\nCWE: CWE-415: Double Free\n\nDescription: In order to validate initial packet, OpenSSL QUIC stack default\npacket handler (port_default_packet_handler()) creates a so-called QRX object.\nIf the initial packet validates successfully with QRX object, the default packet\nhandler proceeds to channel (connection object) creation. The QRX object used\nfor packet validation is passed to port_bind_channel(), so it becomes part of\nthe newly created connection. If port_bind_channel() fails, then it also frees\nthe QRX object. Once port_bind_channel() returns, the port_default_packet_handler()\ndetects the failure and proceeds to the error branch, where the same QRX object is\nfreed for the second time.\n\nThe failure in port_bind_channel() function can be induced with a relatively\nlow effort by a malformed (non RFC 9000 compliant) INITIAL packet. If the packet\ncarries DCID (destination connection ID) which is shorter than 8 bytes, then\nport_bind_channel() jumps to the error path after ossl_quic_lcidm_enrol_odcid()\ndetects that the DCID has invalid length.\n\nFIPS impact: no\nThe FIPS module is not affected, as the QUIC implementation is outside of\nthe OpenSSL FIPS module boundary."
}
],
"metrics": [
{
"format": "other",
"other": {
"content": {
"text": "Moderate"
},
"type": "https://openssl-library.org/policies/general/security-policy/"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-415",
"description": "CWE-415 Double Free",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"orgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
"shortName": "openssl",
"dateUpdated": "2026-08-25T12:59:04.715Z"
},
"references": [
{
"name": "OpenSSL Advisory",
"tags": [
"vendor-advisory"
],
"url": "https://openssl-library.org/news/secadv/20260825.txt"
},
{
"name": "4.0.2 git commit",
"tags": [
"patch"
],
"url": "https://github.com/openssl/openssl/commit/a14a1deac403522fbeafabcb198503cf6caa7dc4"
},
{
"name": "3.6.4 git commit",
"tags": [
"patch"
],
"url": "https://github.com/openssl/openssl/commit/70cebd74d3592f5272945501b58a60374c4e13af"
},
{
"name": "3.5.8 git commit",
"tags": [
"patch"
],
"url": "https://github.com/openssl/openssl/commit/967582d5037f01a26b6d19beae19af62a1b15c3c"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "QUIC Server May Trigger Double Free When Processing INITIAL Packet",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
},
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.5,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "NONE"
}
},
{
"other": {
"type": "ssvc",
"content": {
"timestamp": "2026-08-25T14:15:00.501697Z",
"id": "CVE-2026-18798",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-08-25T14:15:04.879Z"
}
}
]
}
}