CVE-2025-58183 is a vulnerability in tar.Reader of GNU tar pax 1.0 sparse files where no maximum size is set on the number of sparse region data blocks. This can lead to unbounded memory allocation when processing maliciously crafted archives, especially from compressed sources, potentially causing denial of service due to resource exhaustion. The CVSS score is low (3.3) with impact limited to availability. No known exploits or patches are currently reported.