libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.
PUBLISHED5.2CWE-416
Problem type
Affected products
libexpat project
libexpat
< 2.8.2 - AFFECTED
References
GitHub Security Advisories
GHSA-m2mm-5w64-p8p7
libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks...
https://github.com/advisories/GHSA-m2mm-5w64-p8p7libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.
JSON source
https://cveawg.mitre.org/api/cve/CVE-2026-56412Click to expand
{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-56412",
"assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"assignerShortName": "mitre",
"dateUpdated": "2026-06-21T15:58:59.347Z",
"dateReserved": "2026-06-21T15:58:58.955Z",
"datePublished": "2026-06-21T15:58:59.347Z",
"state": "PUBLISHED"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"shortName": "mitre",
"dateUpdated": "2026-06-21T15:58:59.347Z"
},
"descriptions": [
{
"lang": "en",
"value": "libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219."
}
],
"affected": [
{
"vendor": "libexpat project",
"product": "libexpat",
"defaultStatus": "unaffected",
"versions": [
{
"version": "0",
"status": "affected",
"versionType": "semver",
"lessThan": "2.8.2"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"description": "CWE-416 Use After Free",
"cweId": "CWE-416",
"type": "CWE"
}
]
}
],
"references": [
{
"url": "https://github.com/libexpat/libexpat/pull/1278"
}
],
"metrics": [
{
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
],
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
"attackVector": "LOCAL",
"attackComplexity": "HIGH",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"availabilityImpact": "LOW",
"baseScore": 4.9,
"baseSeverity": "MEDIUM"
}
}
]
}
}
}