The eMudhra certificate-authority incident we covered in October has widened. Eight intermediate CA keys were found to be trivially recoverable; now the Indian CA has revoked eight more intermediate CAs whose keys were not weakened, because it cannot show that those keys were handled as its own rules require. The Hacker News reports the eight RSA CAs were revoked late last week, and eMudhra’s incident report gives the revocation date as November 7, using the reason code “cessationOfOperation” rather than a key-compromise code. Participants in the Mozilla Bugzilla thread have asked why.
The report, which eMudhra posted to Mozilla’s bug tracker on November 10, traces both problems to one key ceremony on April 30, 2025. Sixteen intermediate CA keys (eight ECDSA P-384 and eight RSA-4096) were generated on a hardware security module and then moved to hardware from a different vendor with a custom Python script that wrapped and unwrapped each key. For the ECDSA keys, a defect in the read-back code truncated the private value, so the certified keys could be recovered from public information. For the RSA keys, the report says every signature still verifies against the certified key, but the same read-and-recreate step handled private-key attributes in the memory of a Python process on the ceremony computer, so eMudhra “cannot positively demonstrate” compliance with section 6.2.6 of its own certification practice statement. It says it identified that issue in early November after discussions with root programs. On October 19 eMudhra had told Mozilla that “the RSA issuers went through a different path as per our assessment of the code and are therefore not impacted”; The Hacker News says the company later described its early answers as reflecting only what its teams had gathered so far.
Per the report, the four RSA “G2C” issuers were placed in production in May 2026 and issued end-entity certificates, while the eight ECDSA issuers and four RSA “G2B” issuers issued none. The Hacker News counts 195 certificates in the company’s list, 130 from EM DV TLS CA - G2C, 63 from EM OV TLS CA - G2C and 2 from the code-signing CA, EM OV CS CA - G2C, and says the holders have been moved to new certificates, which the report also states. eMudhra says it knows of no misuse (as relayed by The Hacker News). Its remediation plan includes a hard stop on issuance from its emSign Root CA - G1 hierarchy before November 16, an inventory of all its CA keys by November 30, and an independent review, which The Hacker News says is being done by KPMG, due December 4.
The wider trust changes continue. Microsoft updated its security-response post on November 10: starting November 16 it will remove the remaining 10 eMudhra roots from the Windows trusted root list, with Edge and WebView2 receiving an update the same day, and Azure Linux removing them on that date. Per The Hacker News, quoting eMudhra’s phase-out schedule, Chrome and Firefox will not trust G1 certificates issued after November 16, and Apple ends trust in all G1 certificates on November 30. See also our earlier post on Windows removing trust in eMudhra roots.
How to check if you’re affected
Affected products are mainly the certificates and software tied to the eMudhra (emSign) hierarchy. This list follows The Hacker News and the sources below.
- Certificate holders: The Hacker News says eMudhra publishes a list of the affected certificates and that holders can also search Certificate Transparency logs for the revoked G2C TLS issuers (we did not read the list itself). eMudhra says affected holders have been moved to new certificates; our suggestion is to confirm that yours no longer chains to a revoked G2C issuer.
- Anyone relying on certificates chaining to emSign Root CA - G1 or the other remaining eMudhra roots: Microsoft’s timetable starts November 16 for Windows, Edge, WebView2 and Azure Linux images, and some other Microsoft products follow later; see the MSRC table for each product’s date. The .NET SDK, for instance, is planned for December 2026.
- macOS command-line tools: Apple says the fix for
curlandgitaccepting the compromised certificates shipped in macOS 27.2.1, 26.7.3 and 15.8.3. If you can’t update, Apple’s support note says to remove the affected root certificates from/etc/ssl/cert.pem. - Software that ships its own CA bundle or doesn’t check revocation: the incident tracking page (The Hacker News says it is run by Dennis Jackson, who investigated the keys for Mozilla) says these clients need a software update, not just a patched OS or browser, and offers a test page to see whether a client still trusts the compromised intermediates.
Sources
- Mozilla Bugzilla 2083449: Private key compromise of eMudhra Intermediate Certificates (eMudhra’s full incident report is comment 82)
- eMudhra Intermediate CA Compromise (incident tracking page)
- eMudhra: Statement on Recent Certificate Security Incident
- Microsoft Security Response Center: Microsoft’s response to compromised eMudhra certificate authority keys
- Apple Support: About the compromised eMudhra intermediate CAs
- The Hacker News: eMudhra Revokes 8 More CAs It Previously Declared Unaffected by Key Compromise