Read the docs
TI-2026-18358 Aliases CVE-2026-22866GHSA-c6rr-7pmc-73wc

ENS DNSSEC Oracle Vulnerable to RSA Signature Forgery via Missing PKCS#1 v1.5 Padding Validation

Priority MEDIUM 47CWE-347Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-347.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00201 10th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ensdomainsens-contractsup to 1.6.2—No fix listedCNA
—@ensdomains/ens-contracts (npm)up to 1.6.2—No fix listedGHSA-c6rr-7pmc-73wc
  • ens-contracts Vendorensdomains Affected up to 1.6.2 Fixed in — No fix listed CNA
  • @ensdomains/ens-contracts (npm) Vendor— Affected up to 1.6.2 Fixed in — No fix listed GHSA-c6rr-7pmc-73wc

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:ens.domains:ethereum_name_service:*:*:*:*:*:*:*:*up to 1.6.2Vulnerableensdomains
  • cpe:2.3:a:ens.domains:ethereum_name_service:*:*:*:*:*:*:*:* Versions up to 1.6.2 Vulnerable ·ensdomains

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-22866
  2. 2026-10-03 Alias added: GHSA-c6rr-7pmc-73wc

References

Patch 3

Advisory 1

Other 1

  • TI-2023-20046 .eth registrar controller can shorten the duration of registered names CVSS 3.1MEDIUM 6.5
  • TI-2020-04288 Ethereum Name Service - Malicious takeover of previously owned ENS names CVSS 3.1HIGH 8.7

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences