RHSA-2025:22871

In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

In libexpat before 2.2.8, crafted XML input could fool the parser into changing from DTD parsing to document parsing too early; a consecutive call to XML_GetCurrentLineNumber (or XML_GetCurrentColumnNumber) then resulted in a heap-based buffer over-read.

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for m_groupSize.

addBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

defineAttribute in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

lookup in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

nextScaffoldPart in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

storeAtts in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

Expat (aka libexpat) before 2.4.4 has an integer overflow in the doProlog function.

In Expat (aka libexpat) before 2.4.5, an attacker can trigger stack exhaustion in build_model via a large nesting depth in the DTD element.

In Expat (aka libexpat) before 2.4.5, there is an integer overflow in copyString.

In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML_ExternalEntityParserCreate in out-of-memory situations.

libexpat through 2.5.0 allows a denial of service (resource consumption) because many full reparsings are required in the case of a large token for which multiple buffer fills are needed.

A stack overflow vulnerability exists in the libexpat library due to the way it handles recursive entity expansion in XML documents. When parsing an XML document with deeply nested entity references, libexpat can be forced to recurse indefinitely, exhausting the stack space and causing a crash. This issue could lead to denial of service (DoS) or, in some cases, exploitable memory corruption, depending on the environment and library usage.

libexpat in Expat before 2.7.2 allows attackers to trigger large dynamic memory allocations via a small document that is submitted for parsing.