Ubuntu removes two root CAs after eMudhra certificate authority compromise

The private keys of Indian certificate authority eMudhra were publicly demonstrated as compromised on October 20, 2026. Because eMudhra itself was not a direct root trust on Ubuntu but operated through cross-signatures from emSign Root TLS CA – G3 and Comodo AAA Certificate Services, Ubuntu removed both roots from its trust store. Fixes are available for all supported releases from Trusty (14.04) through Stonking (26.10), with older LTS releases requiring Ubuntu Pro/ESM access. Desktop users running browsers as snap packages should note that snaps maintain separate trust stores and refresh automatically four times daily.

Affected releases and remediation

• Removed roots: emSign Root TLS CA – G3 and Comodo AAA Certificate Services (the latter already absent in Ubuntu 22.04+ prior to this update)
• Attack vector: Compromised eMudhra private keys allow fraudulent X.509 certificate signing, enabling man-in-the-middle attacks against any TLS endpoint
• Limitations of mitigations: Public key pinning and DNS CAA records can detect fraudulent certificates but require TLS application support and are not widely deployed
• Desktop caveat: Browser snaps do not use the system ca-certificates trust store; they update independently via snap refresh (four times daily by default)
• ESM coverage: Ubuntu 20.04 LTS and older require Ubuntu Pro subscription for the fix; Pro is free for up to 5 machines (50 for community members)

Why it matters

The cross-signature model in PKI creates systemic vulnerability: a compromised intermediate CA can undermine trust in multiple root stores. Ubuntu's removal of two established roots demonstrates the cascading operational impact when cross-signed authorities fail. Organizations relying on certificates chaining through these roots for internal or regional services may experience unexpected connectivity failures after updating.