---
title: "CVE-2026-115557: Python ssl - Security Enhancement"
description: "Python ssl module contains a security enhancement caused by adding a denylist for known compromised certificates, letting users avoid connections with compromised certificates, exploit requires no special conditions."
url: https://panop.io/threat-heartbeat/CVE-2026-115557/
---

# CVE-2026-115557 Python ssl - Security Enhancement

Python ssl module contains a security enhancement caused by adding a denylist for known compromised certificates, letting users avoid connections with compromised certificates, exploit requires no special conditions.

CVSS base score 9.4 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.53% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-115557)

## Details

Type

Security Enhancement

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Published

24 October 2026

Updated

26 October 2026

Weakness

[CWE-299](https://cwe.mitre.org/data/definitions/299.html)

## Vendor fix

Update to the latest Python version containing the denylist feature.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-115557](https://nvd.nist.gov/vuln/detail/CVE-2026-115557)
- [https://github.com/python/cpython/commit/a17d9ef549008133eadf20689b1f4787902efe5b](https://github.com/python/cpython/commit/a17d9ef549008133eadf20689b1f4787902efe5b)
- [https://github.com/python/cpython/commit/e2a9dd97ef9571c710ac0afaa834c8879aebce78](https://github.com/python/cpython/commit/e2a9dd97ef9571c710ac0afaa834c8879aebce78)
- [https://github.com/python/cpython/commit/7dd8b4736a1419750b94a388e6d158be15836fe6](https://github.com/python/cpython/commit/7dd8b4736a1419750b94a388e6d158be15836fe6)
- [https://github.com/python/cpython/commit/e4f63e65a93cf44c14274aa987e644b8c003625e](https://github.com/python/cpython/commit/e4f63e65a93cf44c14274aa987e644b8c003625e)
- [https://github.com/python/cpython/commit/e9bf2cf84eebf838a1edaa1c648c2b36345b99d3](https://github.com/python/cpython/commit/e9bf2cf84eebf838a1edaa1c648c2b36345b99d3)
- [https://github.com/python/cpython/commit/c7fd7edf7e0d122a3973cf676fae21b6aaa650a8](https://github.com/python/cpython/commit/c7fd7edf7e0d122a3973cf676fae21b6aaa650a8)
- [https://emudhra.we-have-a-problem.com/](https://emudhra.we-have-a-problem.com/)
- [https://github.com/python/cpython/issues/160040](https://github.com/python/cpython/issues/160040)
- [https://mail.python.org/archives/list/security-announce@python.org/thread/FNAJMZV6XQYLVPABNINDMF3VF66AYLW4/](https://mail.python.org/archives/list/security-announce@python.org/thread/FNAJMZV6XQYLVPABNINDMF3VF66AYLW4/)
- [http://www.openwall.com/lists/oss-security/2026/10/24/5](http://www.openwall.com/lists/oss-security/2026/10/24/5)
- [https://github.com/python/cpython/commit/21a50891ab4be2e9955239e625ae2b40c6b1854d](https://github.com/python/cpython/commit/21a50891ab4be2e9955239e625ae2b40c6b1854d)
- [https://github.com/python/cpython/commit/36cd295f32fc9ba19399e01abee91231440a41dd](https://github.com/python/cpython/commit/36cd295f32fc9ba19399e01abee91231440a41dd)
- [https://github.com/python/cpython/commit/e4500d8a437ee5b988a5410cb9b59d177aa01370](https://github.com/python/cpython/commit/e4500d8a437ee5b988a5410cb9b59d177aa01370)
- [http://www.openwall.com/lists/oss-security/2026/10/20/29](http://www.openwall.com/lists/oss-security/2026/10/20/29)
- [https://github.com/python/cpython/commit/48d9b2712cd52206c7a5882d0fdca4863ed65e93](https://github.com/python/cpython/commit/48d9b2712cd52206c7a5882d0fdca4863ed65e93)
- [https://github.com/python/cpython/commit/98f0e4ed349f370dc8a00366da1a9797e11c9ed5](https://github.com/python/cpython/commit/98f0e4ed349f370dc8a00366da1a9797e11c9ed5)
- [https://github.com/python/cpython/commit/af52b41afa4330fb38583db553631baa2f122f90](https://github.com/python/cpython/commit/af52b41afa4330fb38583db553631baa2f122f90)
- [https://github.com/python/cpython/pull/160042](https://github.com/python/cpython/pull/160042)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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