SSRF in Ethereum Web3.py
CVE-2026-111171
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/ethereum/web3.py/pull/3875 (issue-tracking, technical-description, patch)
- github.com/ethereum/web3.py/blob/c8c1ed0c9e77e1a8b74902e6a6825e0b00534b10/web3/… (technical-description)
- github.com/ethereum/web3.py/security/advisories/GHSA-5hr4-253g-cpx2 (related, vendor-advisory)
- github.com/ethereum/web3.py (product)
- www.vulncheck.com/advisories/web3-py-7.15.0-through-7.16.0-and-8.0-0b2-through-… (third-party-advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0
Frequently asked questions
- What is CVE-2026-111171?
- CVE-2026-111171 is a medium-severity vulnerability in Ethereum Web3.py, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.4/10. Published 2026-10-15.
- How severe is CVE-2026-111171?
- Medium severity. CVSS v3 base score is 5.4 out of 10.