CVE-2026-40072: web3.py affected by SSRF via CCIP Read (EIP-3668) OffchainLookup URL handling

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-09 · updated 2026-10-26
Weakness: CWE-918

Description

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 destination validation. CCIP Read is enabled by default (global_ccip_read_enabled = True on all providers), meaning any application using web3.py's .call() 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 eth_call / .call() 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. This vulnerability is fixed in 7.15.0 and 8.0.0b2.

Affected products

ethereum web3.py: from 6.1.0 before 7.15.0; 6.0.0, 6.0.0-beta10, 6.0.0-beta11, 6.0.0-beta3, 6.0.0-beta4, 6.0.0-beta5 (+5) — fixed in 7.15.0

How to fix

Upgrade to a fixed version: ethereum web3.py 7.15.0. Check the vendor advisory for mitigations.

References

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