New Delhi: The private keys of eight intermediate certificates issued by the Indian certificate authority eMudhra were compromised, and researchers found they could be recovered directly from the public certificates because they were generated with far too little randomness.
According to members of Mozilla's cryptography team, a researcher reported the issue on the evening of October 17. Anyone holding one of the keys could issue a fraudulent but trusted certificate for any website and impersonate servers to intercept or modify traffic.
Chrome, Firefox, Apple and Microsoft blocked the certificates within hours. Cloudflare deployed emergency fixes across its network, and the Go programming language released versions 1.27.3 and 1.26.10 that reject chains containing the keys.
Security researcher Scott Helme said he recovered all eight private keys from the public certificates on his laptop in under a second, and that one of them is the number 4; the rest are whole numbers below 256. He said an AI agent did the same from a single prompt.
In a filing with the BSE, eMudhra said a flaw in a key generation ceremony held on April 30, 2025 produced a second, weak set of keys alongside the intended ones, and the weak set was published to browser root stores. The company said its infrastructure was not breached, no data was leaked and its roots and other intermediate CAs were unaffected.
The eight certificates span domain-validated, organisation-validated, extended-validated and code-signing categories. Alongside Go's security releases, projects such as NSS, Python certifi and Homebrew issued fixes. Chrome is removing the related root from its root store, a change expected to reach every device by October 27.
eMudhra's certificates are used by many services, including government websites. The company has revoked the eight certificates.