20th October 2026
The personal keys of eight eMudhra intermediate CA certificates have been compromised. They sequence to roots trusted by the Mozilla, Microsoft, Apple and Chrome base programs and by many downstream rely stores.
How do we know?
To display that the keys are compromised, the first newsman Wayne signed the following communication alongside the personal key of all of the eight intermediate CAs and reported it to the Root Program Teams on the 17th of October:
We have a issue current - Wayne
proof.zip contains the message, and for all intermediate the certificate, its community key and a signature on the message. To verify alongside OpenSSL:
openssl x509 -in EM-DV-TLS-CA-G3B.crt.pem -noout -pubkey | diff - EM-DV-TLS-CA-G3B.pub.pem openssl dgst -sha384 -verify EM-DV-TLS-CA-G3B.pub.pem -signature EM-DV-TLS-CA-G3B.sig message.txt
What actions have been taken?
The base programs and many downstream rely stores have taken act to defend their users. The certificates have been blocked in Firefox and Chrome since the 17th of October, in Apple devices since the 19th and in Microsoft since the 20th.
The matter was responsibly disclosed to downstream rely stores on the 19th of October. Many have already released updates or are in the procedure of releasing updates.
What are the consequences?
An attacker alongside the personal key of any of the compromised intermediate CAs could impersonate any website or service.
This has already been remediated by Mozilla, Microsoft, Apple, and Chrome for their users through their tools for distributing revocation data specified as OneCRL, CRLite and CRLSets.
The CA has additionally revoked the compromised intermediate certificates. However, many another clients do not consume revocation data and necessitate application updates to justify they no longer rely the compromised intermediates.
Does your client motionless rely the compromised intermediates?
| Intermediate CA | Chains to | Result |
|---|
What actions can users take?
Users should update their browsers and functioning systems to the latest versions as shortly as possible.
What concerning developer application and packages?
Add additional at github.com/galadran/we-have-a-problem.com.
Are there workarounds for Linux?
Until a allocation ships an updated ca-certificates package, expert users can distrust the affected roots in the scheme rely store. This is NOT recommended for average users.
On Debian and Ubuntu, run as root:
sed -i \ -e 's|^mozilla/emSign_ECC_Root_CA_-_G3.crt|!&|' \ -e 's|^mozilla/Comodo_AAA_Services_root.crt|!&|' \ /etc/ca-certificates.conf && update-ca-certificates
On Alpine, run as root:
apk add ca-certificates && sed -i -e 's|^mozilla/emSign_ECC_Root_CA_-_G3.crt|!&|' \ /etc/ca-certificates.conf && update-ca-certificates
On Fedora, RHEL, CentOS Stream, Rocky Linux, AlmaLinux and Amazon Linux 2023, run as root:
d=/etc/pki/ca-trust/source/blocklist; [ -d $d ] || d=/etc/pki/ca-trust/source/blacklist trust extract --overwrite --format=pem-bundle \ --filter='pkcs11:object=Comodo%20AAA%20Services%20root;type=cert' \ $d/Comodo_AAA_Services_root.pem && trust extract --overwrite --format=pem-bundle \ --filter='pkcs11:object=emSign%20ECC%20Root%20CA%20-%20G3;type=cert' \ $d/emSign_ECC_Root_CA_-_G3.pem && update-ca-trust
On openSUSE and SLES, run as root:
d=/etc/pki/trust/blocklist; [ -d $d ] || d=/etc/pki/trust/blacklist trust extract --format=pem-bundle \ --filter='pkcs11:object=Comodo%20AAA%20Services%20root;type=cert' \ $d/Comodo_AAA_Services_root.pem && trust extract --format=pem-bundle \ --filter='pkcs11:object=emSign%20ECC%20Root%20CA%20-%20G3;type=cert' \ $d/emSign_ECC_Root_CA_-_G3.pem && update-ca-certificates
On Arch Linux, run as root:
trust extract --format=pem-bundle \ --filter='pkcs11:object=emSign%20ECC%20Root%20CA%20-%20G3;type=cert' \ /etc/ca-certificates/trust-source/blocklist/emSign_ECC_Root_CA_-_G3.pem && update-ca-trust
On NixOS, add to your configuration:
security.pki.caCertificateBlacklist = [ "Comodo AAA Services root" "emSign ECC Root CA - G3" "emSign Root CA - C1" "emSign ECC Root CA - C3" ];
What actions can rely shop operators take?
Please see this thread in Mozilla's dev-security-policy forum.
Which intermediates were compromised?
Fingerprints, SPKI hashes, serial numbers and CCADB document IDs for the eight intermediates, including the Sectigo cross-signs, are in affected-certificates.json.
Site published by Dennis Jackson. The origin is on GitHub and PRs are welcome.
