oesa-2026-3669
Vulnerability from osv_openeuler
expat is a stream-oriented XML parser library written in C. expat excels with files too large to fit RAM, and where performance and flexibility are crucial.
Security Fix(es):
Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.(CVE-2026-66046)
Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.(CVE-2026-76641)
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.(CVE-2026-76957)
| URL | Type | |
|---|---|---|
{
"affected": [
{
"ecosystem_specific": {
"aarch64": [
"expat-2.2.9-33.oe2003sp4.aarch64.rpm",
"expat-debuginfo-2.2.9-33.oe2003sp4.aarch64.rpm",
"expat-debugsource-2.2.9-33.oe2003sp4.aarch64.rpm",
"expat-devel-2.2.9-33.oe2003sp4.aarch64.rpm"
],
"noarch": [
"expat-help-2.2.9-33.oe2003sp4.noarch.rpm"
],
"src": [
"expat-2.2.9-33.oe2003sp4.src.rpm"
],
"x86_64": [
"expat-2.2.9-33.oe2003sp4.x86_64.rpm",
"expat-debuginfo-2.2.9-33.oe2003sp4.x86_64.rpm",
"expat-debugsource-2.2.9-33.oe2003sp4.x86_64.rpm",
"expat-devel-2.2.9-33.oe2003sp4.x86_64.rpm"
]
},
"package": {
"ecosystem": "openEuler:20.03-LTS-SP4",
"name": "expat",
"purl": "pkg:rpm/openEuler/expat\u0026distro=openEuler-20.03-LTS-SP4"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.2.9-33.oe2003sp4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"severity": "High"
},
"details": "expat is a stream-oriented XML parser library written in C. expat excels with files too large to fit RAM, and where performance and flexibility are crucial.\r\n\r\nSecurity Fix(es):\n\nExpat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType-\u0026gt;defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.(CVE-2026-66046)\n\nExpat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.(CVE-2026-76641)\n\nlibexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.(CVE-2026-76957)",
"id": "OESA-2026-3669",
"modified": "2026-09-05T15:03:45Z",
"published": "2026-09-05T15:03:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-3669"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-66046"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-76641"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-76957"
}
],
"schema_version": "1.7.2",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "expat security update",
"upstream": [
"CVE-2026-66046",
"CVE-2026-76641",
"CVE-2026-76957"
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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