CVE-2026-59144 is a stack-based buffer overflow vulnerability in the Perl module Data::RingBuffer::Shared versions prior to 0.04. The vulnerability occurs because the ring_read_seq function performs a memcpy operation using an elem_size value read directly from a memory-mapped segment without validating that elem_size does not exceed the fixed 8-byte size of the destination buffer. Although the ring_validate_header function checks capacity overflow and total size consistency, it does not limit elem_size against the destination size. A local attacker who can modify the backing file can craft a valid header with a large elem_size, causing ring_read_seq to overflow the stack buffer and corrupt adjacent stack frames.

Successful exploitation can lead to stack corruption, potentially allowing arbitrary code execution, denial of service, or other severe impacts due to memory corruption. The vulnerability has a CVSS score of 9.8 (critical), indicating high impact on confidentiality, integrity, and availability. Exploitation requires local write access to the backing file, which limits the attack vector to local or similarly privileged users.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a patch is available, restrict local write access to the backing file used by Data::RingBuffer::Shared to trusted users only. Monitor for updates from the EGOR project or CPAN security advisories for an official fix.