How severe is CVE-2026-27448?

CVE-2026-27448 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-27448 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27448?

CVE-2026-27448 affects Pyopenssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-27448?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-27448 have an EU (EUVD) identifier?

Yes. CVE-2026-27448 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12675.

When was CVE-2026-27448 published?

CVE-2026-27448 was published on 2026-03-18 and last updated on 2026-06-17.

CVE-2026-27448

CVE-2026-27448 is a medium-severity vulnerability in Pyopenssl with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-636.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 1.7
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12675
Weakness: CWE-636
Affected product: Pyopenssl
Published: 2026-03-18
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-27448?: 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 severe is CVE-2026-27448?: CVE-2026-27448 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-27448 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27448?: CVE-2026-27448 affects Pyopenssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-27448?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-27448 have an EU (EUVD) identifier?: Yes. CVE-2026-27448 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12675.
When was CVE-2026-27448 published?: CVE-2026-27448 was published on 2026-03-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:pyopenssl:pyopenssl:*:*:*:*:*:*:*:*

More vulnerabilities in Pyopenssl

CVE-2026-27459 — Critical (CVSS 9.8): pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a…
CVE-2018-1000807 — High (CVSS 8.1): Python Cryptographic Authority pyopenssl version prior to version 17.5.0 contains a CWE-416: Use After Free…

All CVEs affecting Pyopenssl →

Other CWE-636 vulnerabilities

CVE-2026-22034 — Critical (CVSS 9.8): Snuffleupagus is a module that raises the cost of attacks against website by killing bug classes and providing a…
CVE-2024-3729 — Critical (CVSS 9.8): The Frontend Admin by DynamiApps plugin for WordPress is vulnerable to improper missing encryption exception handling…
CVE-2026-40525 — Critical (CVSS 9.1): OpenViking prior to version 0.3.9 contains an authentication bypass vulnerability in the VikingBot OpenAPI HTTP route…
CVE-2024-43532 — High (CVSS 8.8): Remote Registry Service Elevation of Privilege Vulnerability
CVE-2025-54870 — High (CVSS 8.7): VTun-ng is a Virtual Tunnel over TCP/IP network. In versions 3.0.17 and below, failure to initialize encryption modules…
CVE-2026-54762 — High (CVSS 8.6): Traefik is an HTTP reverse proxy and load balancer. From 3.7.0-ea.1 until 3.7.5, there is a medium severity…

Browse all CWE-636 vulnerabilities →