certifi bundles emSign root CAs with compromised intermediate CA keys
The source advisory has changed since this explanation was prepared. Check the current technical data and original advisory below.
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.
What to do
Upgrade to 2026.10.19 or later, and rebuild container images that vendor certifi.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | certifi | >= 2019.03.09, < 2026.10.19 | 2026.10.19 |
References
- https://github.com/certifi/python-certifi/security/advisories/GHSA-6q48-6c7w-9gw2
- https://discuss.python.org/t/information-for-python-users-regarding-emudhra-emsign-ca-certificate-security-incident/109576
- https://emudhra.we-have-a-problem.com
- https://github.com/certifi/python-certifi
- https://pypi.org/project/certifi
- https://github.com/advisories/GHSA-6q48-6c7w-9gw2
- CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-295- Platform
- Python (PyPI)
- Package
certifi- Disclosed
- 20.10.2026
- Updated
- 21.10.2026 00:17
Sources and licenses · Edited or translated by DockRay; source rights and applicable licenses are retained.
OSV / GitHub Advisory Database - GHSA-6q48-6c7w-9gw2 - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-4320 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: certifi
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 12.2022 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
- Medium 1
- Low 1
Disclosures per year
- 2022: 1
- 2023: 1
- 2024: 1
- 2025: 0
- 2026: 1
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