Affected: Alpaquita:23: expat, Alpaquita:25: expat, Alpaquita:stream: expat, BellSoft Hardened Containers:23: expat, BellSoft Hardened Containers:25: expat, BellSoft Hardened Containers:stream: expat

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.

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.

Affected: openEuler:20.03-LTS-SP4: expat

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…

expat-2.8.4-1.1 on GA media

expat: libexpat: Integer Overflow Vulnerability Leading to Information Disclosure or Code Execution expat: Expat: Denial of Service via quadratic complexity in attribute processing expat: Expat: Denial of Service via XML external entity parsing libexpat: libexpat: Denial of Service via hash flooding attack with crafted XML libexpat: libexpat: Memory corruption vulnerability allows arbitrary code execution or denial of service

Affected: Ubuntu:Pro:14.04:LTS: coin3, Ubuntu:Pro:14.04:LTS: expat, Ubuntu:Pro:14.04:LTS: vnc4, Ubuntu:Pro:14.04:LTS: vtk, Ubuntu:Pro:14.04:LTS: xmlrpc-c, Ubuntu:Pro:16.04:LTS: expat, Ubuntu:Pro:16.04:LTS: ayttm, Ubuntu:Pro:16.04:LTS: cableswig, Ubuntu:16.04:LTS: cadaver, Ubuntu:Pro:16.04:LTS: coin3 and 55 more

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.