CVE-2026-1155579.4CriticalCWE-299

CVE-2026-115557: Distrust compromised intermediate certificates in ssl module

Python Software Foundation · CPython

Vendor fix available · Affected: Python Software Foundation CPython · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

45th percentile

050100

Higher than 45% of scored CVEs

9.4CriticalCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

Python has added a denylist for known compromised certificates to the "ssl" module to ensure user safety even without certificate revocation configured. Known compromised certificates will automatically be rejected regardless of the SSLContext policy configuration.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

Python Software Foundation · CPythonbefore 3.11.18; from 3.12.0 before 3.12.16; from 3.13.0 before 3.13.18; from 3.14.0 before 3.14.10; from 3.15.0 before 3.15.2; from 3.16.0a1 before 3.16.0

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Check for Certificate Revocation · Cryptography
Vendor: Python Software Foundation
Published: October 2026
Band: Unlikely (under 1%), October 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-115557 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

6 more references are in the CVE record.