Is CVE-2026-115557 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-115557 being exploited in the wild.

How severe is CVE-2026-115557?

Informational severity, published 24 October 2026.

Which products and versions are affected?

Python all versions receiving the patch.

Is there a fix for CVE-2026-115557?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-115557 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-115557?

Check whether you run Python at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-115557: Python ssl module denylist for compromised certificates

CVE-2026-115557 · Severity: info · Published 2026-10-24

Python has added an automatic denylist of known compromised certificates to its SSL/TLS module to protect applications even when certificate revocation checking is not configured. This ensures that applications using Python cannot be tricked into accepting counterfeit HTTPS certificates from a small set of intermediate certificate authorities whose private keys were leaked, preventing potential man-in-the-middle attacks and impersonation of websites and services.

Technologies: Python. Vendors: Python.

Quick answers

Is CVE-2026-115557 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-115557 being exploited in the wild.
How severe is CVE-2026-115557?: Informational severity, published 24 October 2026.
Which products and versions are affected?: Python all versions receiving the patch.
Is there a fix for CVE-2026-115557?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-115557 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-115557?: Check whether you run Python at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

Python's ssl module now blocks connections using a hardcoded denylist of compromised intermediate CA certificates, regardless of SSLContext trust policy configuration. This targets the specific eMudhra intermediate certificates whose private keys were compromised due to flawed key generation, preventing chains containing these intermediates from being validated. The fix is a defensive measure for clients that do not enforce Certificate Transparency or consume revocation information.

Affected products

Python Python all versions receiving the patch

Timeline

2026-10-20: disclosed: eMudhra intermediate CA compromise disclosed
2026-10-24: other: Advisory published

References

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