GHSA-6q48-6c7w-9gw2: certifi bundles emSign root CAs with compromised intermediate CA keys
Certifi versions before 2026.10.18 include the emSign ECC Root CA - G3 root certificate in their bundled CA store. Eight eMudhra intermediate CA certificates that chain to this root have compromised private keys and the CA has revoked them.
An attacker with one of the compromised keys can issue valid-looking certificates for any hostname. If the attacker is also on-path, they can intercept or modify TLS traffic from clients that trust the certifi bundle. Examples include requests, urllib3 and pip, and the Python.org macOS installer.
Certifi 2026.10.18 removed all emSign roots from the bundle. Certifi 2026.10.19 restored the emSign roots that are not affected. Upgrade to 2026.10.19 or later, and rebuild container images that vendor certifi.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/certifito a version that resolves this vulnerability.Fixed in 2026.10.19 - Upgrade
Upgrade
pip/certifito a version that resolves this vulnerability.Fixed in 2026.10.18 - Upgrade
Upgrade
certifito a version that resolves this vulnerability.Fixed in 2026.10.19 - Operational
Rebuild container images that vendor certifi.
Event History
Frequently Asked Questions
Which environments are exposed to interception or modification of TLS traffic?
Clients that use a certifi bundle containing the affected emSign root are exposed when an attacker is also on the network path and possesses one of the compromised eMudhra intermediate CA private keys. Examples named in the advisory include requests, urllib3, pip, and the Python.org macOS installer.
What version should be deployed to remediate the issue?
Upgrade certifi to version 2026.10.19 or later. Version 2026.10.18 removed all emSign roots, while 2026.10.19 restored emSign roots that are not affected.
Are containerized applications covered by a dependency upgrade alone?
No. Container images that vendor certifi must be rebuilt so that they include the updated CA bundle.