critical · 9.1 Patched

certifi bundles emSign root CAs with compromised intermediate CA keys

GHSA-6q48-6c7w-9gw2 · published 20 Oct 2026

How serious is it

  • Severity: critical, CVSS score 9.1 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by GHSA-6q48-6c7w-9gw2?

Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.

Who is affected

  • certifi (PyPI) >= 2019.03.09, < 2026.10.19

How to check

  1. Run pip show certifi in your project to see the installed version, including copies pulled in by other packages.
  2. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.
  3. Or run npx shippable-dev scan localhost:3000 in your project folder. It reads your lockfile and flags this vulnerability along with every other known one.

How to fix

Copies a prompt for Claude Code, Cursor or Codex: it checks your lockfiles for this and upgrades it.
  1. Upgrade certifi to 2026.10.19 or later, commit the lockfile and redeploy.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

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.

Check your whole app

Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.

References

Merged from GitHub Advisory Database. Last updated 23 Oct 2026. All vulnerabilities · RSS · JSON

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