CVE-2026-111171: Web3
Web3.py 7.15.0 through 7.16.0 and 8.0.0b2 through 8.0.0 contains a server-side request forgery vulnerability because _check_ip_blocked() does not unwrap IPv4-mapped IPv6 addresses in CCIP Read URL validation. Malicious contracts can return OffchainLookup URLs with IPv4-mapped IPv6 hosts or AAAA records, making clients with CCIP Read enabled send requests to loopback, private, or link-local services.
Vuln-watch · relayed from the NVD / CVE program; see Source & attribution below
Summary
Web3.py 7.15.0 through 7.16.0 and 8.0.0b2 through 8.0.0 contains a server-side request forgery vulnerability because _check_ip_blocked() does not unwrap IPv4-mapped IPv6 addresses in CCIP Read URL validation. Malicious contracts can return OffchainLookup URLs with IPv4-mapped IPv6 hosts or AAAA records, making clients with CCIP Read enabled send requests to loopback, private, or link-local services.
Severity
Medium (CVSS 6.3), as scored by NVD.
Weakness
- CWE-918
Recommended actions
- Check whether you run or depend on the affected component and version
- Apply the vendor's fix or mitigation from the references below
Source & attribution
This 0xCERT advisory summarises CVE-2026-111171 from the U.S. National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2026-111171. Details may change; refer to the original source for the authoritative record.
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-111171
- https://github.com/ethereum/web3.py
- https://github.com/ethereum/web3.py/blob/c8c1ed0c9e77e1a8b74902e6a6825e0b00534b10/web3/utils/ccip_url_validation.py#L16-L57
- https://github.com/ethereum/web3.py/pull/3875
- https://github.com/ethereum/web3.py/security/advisories/GHSA-5hr4-253g-cpx2
- https://www.vulncheck.com/advisories/web3-py-7.15.0-through-7.16.0-and-8.0-0b2-through-8.0.0-ccip-read-ssrf-bypass
OpenPGP-signed. The signed text of this advisory verifies against the 0xCERT key CCC7 D9EC 9415 723D.
Published 2026-10-15 · last updated 2026-10-15
curl -s https://www.0xcert.com/pgp.asc | gpg --import && curl -s https://www.0xcert.com/advisory/0xCERT-2026-0244/signed.txt | gpg --verify