CVE-2025-59375 is a memory amplification vulnerability in libexpat that allows attackers to trigger excessive dynamic memory allocations by submitting specially crafted XML input. This can cause the parser to allocate hundreds of megabytes of memory from a relatively small input (~250 KiB), resulting in denial-of-service through memory exhaustion. The flaw is limited to availability impact and does not enable arbitrary code execution, data leakage, or privilege escalation. Red Hat rates this vulnerability as Important (high severity) due to its potential for resource exhaustion. Mitigation strategies include input size and complexity restrictions, avoiding compressed or deeply nested XML, and using OS-level resource limits or sandboxing. The vulnerability affects multiple Red Hat products that include libexpat, including Red Hat Enterprise Linux and Red Hat OpenShift components. No explicit patch or fix version is stated in the advisory content provided.

The vulnerability causes denial-of-service by allowing an attacker to cause excessive memory allocation in libexpat, leading to resource exhaustion. It impacts availability only, with no confidentiality or integrity compromise. The exploit requires submission of crafted XML input. In applications like Firefox and Thunderbird that use libexpat transitively, exploitation results in application crashes (app-level DoS). There is no known exploit in the wild reported. The impact is high severity due to potential service disruption but not critical since it does not allow code execution or data compromise.

Red Hat recommends mitigating this vulnerability by limiting the size and complexity of XML inputs before parsing, avoiding compressed or deeply nested XML documents, and applying OS-level resource controls such as ulimit or setrlimit() to cap memory usage. Running the parser in a sandboxed or isolated process with strict memory and CPU limits can also help contain excessive resource consumption. No official patch or fix version is confirmed in the provided data; therefore, users should monitor Red Hat advisories for updates and apply mitigations accordingly.