eMudhra's Weak CA Keys Prompt Withdrawal From SSL/TLS Market
eMudhra generated weak CA keys during a 2025 ceremony, cross‑signed by Sectigo, and has now withdrawn from the global SSL/TLS market. Major browsers and tooling have blocked the certificates, but residual risk remains for systems that haven’t updated their trust stores.
A batch of weak certificate‑authority private keys slipped into eMudhra’s infrastructure, and because browsers and other trust stores still treated the resulting certificates as legitimate, it created a potential foothold for forged TLS or code‑signing credentials. The incident forced eMudhra to pull out of the global SSL/TLS business and triggered a sharp market drop, but the full scope of exposed certificates and remaining risk is still being sorted out.
The error surfaced during a key‑generation ceremony on April 30, 2025, when eMudhra created 16 CA keys using Utimaco hardware security modules. A later analysis suggests eight of those keys were generated with insufficient entropy—values like 4, 56, 66, 115, 155, 156, 230, 237 instead of ~384‑bit random numbers. The company says the flaw was limited to a small fraction of its 40 certifying authorities and that the keys were not used commercially. What we can’t tell from the reporting is whether the remaining eight keys are safe or also compromised, and whether any of the affected intermediates have been used to sign certificates that are still trusted by major browsers.
How the keys went wrong
The bug was in a custom script used during the key‑generation ceremony. A single line truncated each of the eight keys to one byte, turning what should have been 384‑bit random values into tiny integers. Those integers were then cross‑signed by Sectigo’s AAA root in May 2025, which gave the compromised intermediates wide reach across the web. Browsers accepted the resulting certificates because the public keys looked normal, even though the private keys could be brute‑forced in seconds.
Why it mattered
The weak keys were cross‑signed by Sectigo’s AAA root in May 2025, which gave them wide reach across the web. eMudhra’s stock fell about 36 % over three trading days in late October, dropping from roughly ₹540 per share to a 52‑week low of ₹345.60, according to exchange data and local reports. The Ministry of Electronics and Information Technology (MeitY) launched an investigation and said the impact on Indian websites and applications is “very limited,” while eMudhra’s co‑founder Kaushik Srinivasan confirmed that no subscriber data was affected. Still, the incident has eroded confidence in eMudhra’s certificate‑issuing services and prompted the company to voluntarily withdraw from the global SSL/TLS market.
What’s been fixed and what’s left
Major browsers quickly blocked the affected certificates—Chrome on October 17, Firefox on October 19, Apple on October 19 and Microsoft on October 20, according to vendor announcements. Language runtimes and tooling that bundle their own CA stores have shipped patches: Python’s certifi and pip, Go, Rust’s webpki‑roots, Node.js, and various distro‑level ca‑certificates updates. However, embedded devices, container images and some older environments still rely on vendored trust bundles and may need manual rebuilding or updated base images. eMudhra has revoked eight additional intermediates as of November 13, 2026, and stopped issuing new TLS certificates, but until all systems that still trust the compromised keys are updated, the residual risk is confined to environments that haven’t applied the latest truststore fixes or that cache old bundles. The next clear milestone will be the outcome of the MeitY investigation and any regulatory response it triggers.
