PYSEC-2026-4320
See a problem?- Import Source
- https://github.com/pypa/advisory-database/blob/main/vulns/certifi/PYSEC-2026-4320.yaml
- JSON Data
- https://api.osv.dev/v1/vulns/PYSEC-2026-4320
- Aliases
- Published
- 2026-10-20T21:41:50Z
- Modified
- 2026-10-20T22:00:02Z
- Severity
-
- 9.1 (Critical) CVSS_V4 - 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 CVSS Calculator
- Summary
- certifi bundles emSign root CAs with compromised intermediate CA keys
- Details
-
Certifi versions before 2026.10.18 include the
emSign ECC Root CA - G3root 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,urllib3andpip, 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.
- 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
Affected packages
PyPI / certifi
Package
- Name
- certifi
- View open source insights on deps.dev
- Purl
- pkg:pypi/certifi
Affected versions
2019.*
2019.3.9
2019.6.16
2019.9.11
2019.11.28
2020.*
2020.4.5
2020.4.5.1
2020.4.5.2
2020.6.20
2020.11.8
2020.12.5
2021.*
2021.5.30
2021.10.8
2022.*
2022.5.18
2022.5.18.1
2022.6.15
2022.6.15.1
2022.6.15.2
2022.9.14
2022.9.24
2022.12.7
2023.*
2023.5.7
2023.7.22
2023.11.17
2024.*
2024.2.2
2024.6.2
2024.7.4
2024.8.30
2024.12.14
2025.*
2025.1.31
2025.4.26
2025.6.15
2025.7.9
2025.7.14
2025.8.3
2025.10.5
2025.11.12
2026.*
2026.1.4
2026.2.25
2026.4.22
2026.5.20
2026.6.17
2026.7.22
2026.10.18