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Fencer Vulns
medium 5.3

CVE-2023-34449 json

ink! vulnerable to incorrect decoding of storage value when using `DelegateCall`

published 2023-06-14 3 y ago modified 2026-09-10 1 mo ago also GHSA-853p-5678-hv8f , EUVD-2023-1743

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits
0
none known

Summary

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.

Patch / fix

  • crates.io ink 4.2.1
  • crates.io ink_env 4.2.1
  • parity ink! 4.2.1

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
22 mo ago

Exploit prediction

0.97% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/paritytech/ink/security/advisories/GHSA-853p-5678-hv8f referenced PoC, tagged "exploit" by a source, unverified
  • docs.rs https://docs.rs/ink_env/4.2.0/ink_env/call/struct.CallBuilder.html#method.delegate referenced PoC, tagged "exploit" by a source, unverified
  • docs.rs https://docs.rs/ink_env/4.2.0/ink_env/fn.invoke_contract_delegate.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
crates.io ink
>=4.0.0, <4.2.1
4.2.1
crates.io ink_env
>=4.0.0, <4.2.1
4.2.1

Affected products

  • paritytech ink

Classification

Weakness
  • CWE-754 Improper Check for Unusual or Exceptional Conditions
  • CWE-253 Incorrect Check of Function Return Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.