A flaw was found in the xmlSetTreeDoc() function of the libxml2 XML parsing library. This function is responsible for updating document pointers when XML nodes are moved between documents. Due to improper handling of namespace references, a namespace pointer may remain linked to a freed memory region when the original document is destroyed. As a result, subsequent operations that access the namespace can lead to a use-after-free condition, causing an application crash.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.