Compromised eMudhra intermediate certificates

Strategic summary

Cisco Talos identified eight compromised intermediate certificates belonging to the certificate authority eMudhra. Due to a flaw in the key generation process, the private keys were generated with only 3 to 8 bits of entropy instead of the required 384 bits. An attacker with any of these private keys can impersonate any website or service; six TLS certificates have already been blocked by Chrome, Mozilla, and Apple, and two code signing certificates have been blocked by Microsoft. eMudhra has revoked the compromised certificates and stopped issuing new certificates under the G3 root, and the Go team has assigned CVE-2026-111943.

Key findings

• Eight eMudhra intermediate certificates are compromised because their private keys have only 3 to 8 bits of entropy instead of the required 384 bits.
• With any of these private keys, an attacker can impersonate any website or service because the certificates are trusted.
• Six TLS certificates have already been blocked by Chrome, Mozilla, and Apple; two code signing certificates used by Microsoft have also been blocked.
• The cause was a flaw during key generation on April 30, 2025 under the emSign Root TLS CA - G3, where weak P-384 keys were mistakenly used for eight intermediate CA certificates.
• eMudhra has revoked the affected certificates and stopped issuing new certificates under the G3 root; the Go team has assigned CVE-2026-111943.