eMudhra Incident Report: Script Truncated CA Keys, Eight More RSA Intermediates Revoked

eMudhra's incident report, filed on Mozilla's bug tracker on 10 November, puts the cause of its certificate authority compromise in a host-side script: "a single line in that read‑back truncated the private value to its leading byte". It also widens the incident. The 30 April 2025 ceremony behind the eight ECDSA intermediates with recoverable keys produced 16 subordinate CAs, and the eight RSA ones, the G2B and G2C intermediates, were revoked on 7 November.

The RSA intermediates

Their keys weren't truncated. The trouble is how they were handled: the report says eMudhra "cannot positively demonstrate that this key material was in compliance with CPS §6.2.6", the section of its own policy on private keys. Unlike the ECDSA set, the G2C issuers were in use. They "issued end‑entity certificates" from May 2026, the last on 3 November, and a spreadsheet of them is attached to the bug. The revocations cite "cessationOfOperation" as the reason.

eMudhra says it has "no known case of misuse".

What eMudhra commits to

The report promises a hard stop on issuance from the emSign Root CA - G1 hierarchy before 16 November, an inventory of all CA keys by 30 November and an independent review due on 4 December. It arrived a day after the 9 November date eMudhra had set itself.

Reaction on the bug

The researcher who first reported the weak keys answered within two hours that the report "raises more questions than it answers". Other commenters have asked eMudhra to publish the ceremony and import code. Mozilla, Google, Apple and Microsoft hadn't responded to the report on the bug by the morning of 11 November.

Browsers and the G1 root

Mozilla has removed email trust and set a TLS distrust-after date of 16 November 23:59:59 UTC for emSign Root CA - G1 in its NSS root store. Google's 4 November update says G1 certificates will "no longer be trusted by default in Chrome 153 and higher", except those whose earliest Certificate Transparency timestamp falls on or before 16 November 23:59:59 UTC.

What to install

Apple has closed the hole left open in curl, git and other macOS command-line tools. It says that "starting in macOS 27.2.1, these command-line tools stop accepting these certificates", with the same fix in macOS 26.7.3 and 15.8.3. Those releases also drop emSign Root CA - G1 from /etc/ssl/cert.pem.