Vulnerability Description
Ethereum Name Service (ENS) is a distributed, open, and extensible naming system based on the Ethereum blockchain. In versions 1.6.2 and prior, the `RSASHA256Algorithm` and `RSASHA1Algorithm` contracts fail to validate PKCS#1 v1.5 padding structure when verifying RSA signatures. The contracts only check if the last 32 (or 20) bytes of the decrypted signature match the expected hash. This enables Bleichenbacher's 2006 signature forgery attack against DNS zones using RSA keys with low public exponents (e=3). Two ENS-supported TLDs (.cc and .name) use e=3 for their Key Signing Keys, allowing any domain under these TLDs to be fraudulently claimed on ENS without DNS ownership. Apatch was merged at commit c76c5ad0dc9de1c966443bd946fafc6351f87587. Possible workarounds include deploying the patched contracts and pointing DNSSECImpl.setAlgorithm to the deployed contract.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Ens.Domains | Ethereum Name Service | <= 1.6.2 |
Related Weaknesses (CWE)
References
- https://github.com/ensdomains/ens-contracts-bug-62248-pr-509PatchRelease Notes
- https://github.com/ensdomains/ens-contracts/commit/c76c5ad0dc9de1c966443bd946fafPatch
- https://github.com/ensdomains/ens-contracts/security/advisories/GHSA-c6rr-7pmc-7PatchVendor Advisory
FAQ
What is CVE-2026-22866?
CVE-2026-22866 is a vulnerability with a CVSS score of 7.5 (HIGH). Ethereum Name Service (ENS) is a distributed, open, and extensible naming system based on the Ethereum blockchain. In versions 1.6.2 and prior, the `RSASHA256Algorithm` and `RSASHA1Algorithm` contract...
How severe is CVE-2026-22866?
CVE-2026-22866 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-22866?
Check the references section above for vendor advisories and patch information. Affected products include: Ens.Domains Ethereum Name Service.