CVE-2023-34449: ink! is an embedded domain specific language to write smart contracts in Rust for blockchains built on the Sub

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MEDIUM 5.3REMOTEUPGRADE

CVE-2023-34449 is a medium-severity flaw (CVSS 5.3) affecting ink\!. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-253, CWE-754
Published	2023-06-14
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: parity

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-06-14 21:15 UTCPublished CVE record published
2026-06-17 06:03 UTCUpdated Record last modified

parity ink\! UPGRADE

Affected: >= 4.0.0 and < 4.2.1

Fixed in: 4.2.1

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy ink || rpm -q ink || ink --version

2. UPGRADE to 4.2.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ink

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ink

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison ink sudo apt install ink=<VERSION_BEFORE_4.0.0> sudo apt-mark hold ink

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ink sudo dnf downgrade ink-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add ink

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-34449?

ink\!: upgrade to 4.2.1. Exact commands for each OS are on this page.

Is CVE-2023-34449 being exploited?

CVE-2023-34449 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-34449 affect?

CVE-2023-34449 affects ink\!. Severity is medium (CVSS 5.3). 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, eithe

How urgent is CVE-2023-34449?

Priority 44/100. Public exploit reference; Remotely exploitable, no login, no user action

References

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