Executive Summary
Eight intermediate certificate authority (CA) certificates operated by eMudhra have been comprised, triggering an industry-wide response from browser vendors, including Firefox and Chrome, operating system providers, and software maintainers after researchers discovered the certificates’ private keys could be derived from publicly available certificate data. The issue was not caused by a network intrusion or theft of keys. Instead, a flaw during an April 2025 key generation ceremony produced weak cryptographic keys with insufficient randomness, allowing researchers to recover them from the public certificates. Browser vendors rapidly blocked the affected certificates between 17 and 20 October, while eMudhra revoked the intermediates and began migrating affected customers to new certificate hierarchies.
Key Takeaways
- On 17 October, a researcher reported that the private keys for eight eMudhra intermediate CA certificates could be computed from publicly available certificate data due to insufficient randomness in the generated keys. Mozilla reportedly recovered the keys within two hours of receiving the report, and browser vendors began deploying emergency blocks shortly thereafter.
- The affected certificates included domain validation, organization validation, extended validation, and code-signing intermediates. An intermediate CA signs certificates that websites present to users, meaning anyone possessing one of these keys could potentially issue certificates that browsers would otherwise accept as trusted.
- By 20 October, numerous software projects had revoked or blocked trust in the compromised certificates, while updates to Go, NSS, certifi, Rust webpki-roots, Homebrew, Composer, and other trust stores removed or distrusted the affected certificate chains. eMudhra later stated that the flaw originated during a 30 April 2025 key-generation ceremony, that its infrastructure was not compromised, and that it is providing replacement certificates while continuing its root-cause investigation.
