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Findings

CVE-2026-40072

web3.py allows you to interact with the Ethereum blockchain using Python.

Published Apr 9, 2026 · updated Jul 13, 2026 · apeworx web3.py

## Summary web3.py implements CCIP Read / (EIP-3668) by performing HTTP requests to URLs supplied by smart contracts in . The implementation uses these contract-supplied URLs directly (after / template substitution) without any destination validation: - No restriction to (and no opt-in gate for ) - No hostname or IP allowlist - No blocking of private/reserved IP ranges (loopback, link-local, RFC1918) - No redirect target validation (both and follow redirects by default) **CCIP Read is enabled by default** ( on all providers), meaning any application using web3.py's method is exposed without explicit opt-in. This results in **Server-Side Request Forgery (SSRF)** when web3.py is used in backend services, indexers, APIs, or any environment that performs / against untrusted or user-supplied contract addresses. A malicious contract can force the web3.py process to issue HTTP requests to arbitrary destinations, including internal network services and cloud metadata endpoints. --- ## Why This Is a Vulnerability The argument is not that CCIP Read itself is invalid or that web3.py should stop supporting EIP-3668. The issue is that, in server-side deployments (backends, indexers, bots, APIs), the current implementation doesn't provide destination policy controls, such as a validation/override hook, private-range blocking, or redirect target checks, which means contract controlled CCIP URLs can be used as an SSRF primitive. This is consistent with EIP-3668's own security considerations, which recommends that client libraries "provide clients with a hook to override CCIP read calls, either by rewriting them to use a proxy service, or by denying them entirely" and that "this mechanism or another should be written so as to easily facilitate adding domains to allowlists or blocklists." The mitigations I'm suggesting are meant to align with that guidance without breaking CCIP Read support. - **Default-on exposure.** CCIP Read is enabled by default on all web3.py providers ( ). User

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 9, 2026 · NIST NVD

    Detected

    web3.py allows you to interact with the Ethereum blockchain using Python. From 6.0.0b3 to before 7.15.0 and 8.0.0b2, web3.py implements CCIP Read / OffchainLookup (EIP-3668) by performing HTTP requests to URLs supplied by smart contracts in offchain_lookup_payload["urls"]. The implementation uses these contract-supplied URLs directly (after {sender} / {data} template substitution) without any dest

  2. Jun 17, 2026 · NIST NVD

    Updated

    web3.py allows you to interact with the Ethereum blockchain using Python. From 6.0.0b3 to before 7.15.0 and 8.0.0b2, web3.py implements CCIP Read / OffchainLookup (EIP-3668) by performing HTTP requests to URLs supplied by smart contracts in offchain_lookup_payload["urls"]. The implementation uses these contract-supplied URLs directly (after {sender} / {data} template substitution) without any dest

  3. Jul 13, 2026 · GitHub Advisory Database

    Fix available

    web3 fixed in 7.15.0

  4. Jul 13, 2026 · GitHub Advisory Database

    Fix available

    web3 fixed in 7.15.0

  5. Jul 13, 2026 · GitHub Advisory Database

    Updated

    ## Summary web3.py implements CCIP Read / (EIP-3668) by performing HTTP requests to URLs supplied by smart contracts in . The implementation uses these contract-supplied URLs directly (after / template substitution) without any destination validation: - No restriction to (and no opt-in gate for ) - No hostname or IP allowlist - No blocking of private/reserved IP ranges (loopback, link-local, RFC19

Affected

  • PyPI web36.0.0b3 → 7.15.0
  • cpe apeworx/web3.pyversion unspecified
  • cpe apeworx/web3.py6.0.0

Sources

  • CVE.orgVulnerability recordCVE-2026-40072

    Official CVE identifier

    cve.org
  • GitHub Advisory DatabasePackage advisoryGHSA-5hr4-253g-cpx2

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • NIST NVDVulnerability recordCVE-2026-40072

    web3.py allows you to interact with the Ethereum blockchain using Python. From 6.0.0b3 to before 7.15.0 and 8.0.0b2, web3.py implements CCIP Read / OffchainLookup (EIP-3668) by performing HTTP requests to URLs supplied by smart contracts in offchain_lookup_payload["urls"]. The im

    nvd.nist.gov
  • OSV.devPackage advisoryPYSEC-2026-3414

    web3.py: SSRF via CCIP Read (EIP-3668) OffchainLookup URL handling

    osv.dev

References