CVE-2026-27448
LOWDescription
pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 15% of all known CVEs.
References
Related Vulnerabilities
Other CWE-636 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-43532 | High | 8.8 | 12% | - | Fix |
| CVE-2023-28840 | High | 7.5 | 2.7% | - | Fix |
| CVE-2021-1578 | High | 8.8 | 2.0% | - | - |
| CVE-2023-28842 | Medium | 6.8 | 1.4% | - | Fix |
| CVE-2025-21210 | Medium | 4.2 | 1.1% | - | Fix |
| CVE-2024-3729 | Critical | 9.8 | 0.8% | - | Fix |
Common questions
How do I fix CVE-2026-27448?
Published advisories record a fix for 4 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-27448 being actively exploited?
Not that we know of. CVE-2026-27448 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.24% is the estimated probability that it will be exploited in the next 30 days. That is higher than 15% of all scored CVEs.
How severe is CVE-2026-27448?
CVE-2026-27448 has a CVSS v3 base score of 5.3, rated low. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-27448 affect?
Published advisories record a fix for pyopenssl (Debian), pyopenssl (Ubuntu), python-openssl (Ubuntu), python3-openssl (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-23.