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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-c6rr-7pmc-73wc | ENS DNSSEC Oracle Vulnerable to RSA Signature Forgery via Missing PKCS#1 v1.5 Padding Validation |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 25 Feb 2026 16:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ENS DNSSEC Oracle Vulnerable to RSA Signature Forgery via Missing PKCS#1 v1.5 Padding Validation | |
| Weaknesses | CWE-347 | |
| References |
| |
| Metrics |
cvssV4_0
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-02-25T15:47:16.230Z
Reserved: 2026-01-12T16:20:16.746Z
Link: CVE-2026-22866
No data.
Status : Received
Published: 2026-02-25T16:23:25.277
Modified: 2026-02-25T16:23:25.277
Link: CVE-2026-22866
No data.
OpenCVE Enrichment
No data.
Weaknesses
Github GHSA