Published Oct 21, 2026 | 5:03 PM ⚊ Updated Oct 21, 2026 | 5:03 PM
Private keys are supposed to be so large and unpredictable that computers cannot feasibly guess them by brute force.
Synopsis: Comically weak cryptography deployed by Bengaluru-based eMudhra in eight intermediate certificates it issued to verify the legitimacy of websites has left browsermakers, software developers and major technology companies scrambling to plug a gaping hole in internet security. Major browsermakers and operating system developers have blocked the affected certificates.
Comically weak cryptography deployed by Bengaluru-based eMudhra in eight intermediate certificates it issued to verify the legitimacy of websites has left browsermakers, software developers and major technology companies scrambling to plug a gaping hole in internet security.
Google Chrome and Mozilla Firefox have blocked the affected certificates, as have Apple and Microsoft on their platforms.
eMudhra is a certifying authority (CA) that issues digital signature certificates and provides electronic authentication services. Its services are used across government departments and public-sector undertakings (PSUs), including Aadhaar-related authentication and e-signing.
On the internet, CAs vouch for the legitimacy of websites through digital certificates that browsers and other software check before establishing secure connections. On October 17, an independent security researcher found that eight intermediate certificates issued by eMudhra had comically weak private keys.
Private keys are supposed to be so large and unpredictable that computers cannot feasibly guess them by brute force. For the NIST P-384 elliptic-curve standard used in this incident, a private key is typically 384 bits long. An RSA private key is commonly 2,048 or 3,072 bits.
eMudhra’s eight compromised keys, by contrast, were the numbers 4, 56, 66, 115, 155, 156, 230 and 237.
If an intermediate certificate’s private key is exposed, an attacker can use it to issue fraudulent certificates for websites they do not control, making malicious sites appear legitimate. This can be used to trick users into downloading malware, steal sensitive data or intercept communications.
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In a statement, eMudhra said the eight intermediate certificates were created during a key-generation ceremony on April 30, 2025. A key wrap/unwrap step in the procedure produced a second, weak set of keys alongside the original strong keys. The weak keys were published to browser root stores.
The company said the keys were generated using certified hardware security modules, and that the failure lay in the ceremony procedure, not in the absence of such equipment.
The flaw went undetected for about 18 months, including through two independent audit cycles, eMudhra said. The company revoked all eight intermediate certificates on October 19. Seven had never been used in production; the eighth had been deployed but had not issued a single website certificate.
Browsermakers have also moved to distrust the eMudhra elliptic-curve cryptography (ECC) root certificate that signed the intermediates. Mozilla removed the root from its updated trusted certificate list to protect applications that use its trust store but do not receive Firefox’s certificate-revocation updates.
eMudhra said the impact was confined to one customer ecosystem in the United States, whose certificates are being replaced through an alternate, publicly trusted CA hierarchy. It said its digital signature and eSign services, including those used in India, as well as emSigner, CertiNext, emCA, Privatrust and SecurePass, were unaffected.
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Update your browsers to the latest versions. Google Chrome and Firefox have blocked the eight compromised certificates. You can verify whether your browser has received the latest patch here.
CAs are also part of the trust infrastructure used by operating systems, software libraries and Internet of Things devices.
Unlike browser updates, fixes for these systems could take days, weeks or even months to reach users. Check for and install available updates for Windows, Android, Linux distributions and Apple devices. If you are a Linux user, check your distribution for updates to its ca-certificates package.
Update all your other software, too. Applications, developer tools and software packages can rely on certificate stores separate from those used by browsers.
If you use a Mac and work with command-line tools, keep in mind that Apple’s protections do not necessarily extend to every tool installed on the system. You may have to remove the affected roots manually.
(Edited by Dese Gowda)
