CVE-2026-19553 Affecting python3 package, versions <3.12.15-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.4% (33rd percentile)

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  • Snyk IDSNYK-ALPINE322-PYTHON3-20364527
  • published1 Oct 2026
  • disclosed30 Sept 2026

Introduced: 30 Sep 2026

NewCVE-2026-19553  (opens in a new tab)

How to fix?

Upgrade Alpine:3.22 python3 to version 3.12.15-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3 package and not the python3 package as distributed by Alpine. See How to fix? for Alpine:3.22 relevant fixed versions and status.

ssl.SSLContext.wrap_bio() didn't require the server_hostname argument to not be None if ssl.SSLContext.check_hostname was set. Due to a missing parameter check in SSLObject, if the server_hostname argument isn't supplied then hostname verification would be silently skipped.

This defect could lead to programs where certificate hostname verification appeared to be succeeding with SSLContext.check_hostname = True and no ValueError being raised due to misconfiguration.

If the program passes a server_hostname value that isn't an empty string or None to any of these APIs then certificate hostname verification proceeds as expected and the program is not affected by this vulnerability.

Mitigating this vulnerability doesn't require updating Python or applying the patch. To mitigate, pass a valid non-None and non-empty server_hostname value to SSLContext.wrap_bio(), asyncio.create_connection(), or asyncio.loop.start_tls() and certificate hostname verification will proceed as expected. Upgrading to the latest version of Python or applying the patch only changes the behavior from silently skipping hostname verification to raising a ValueError, similar to SSLContext.wrap_socket(), when server_hostname isn't supplied.

CVSS Base Scores

version 3.1