Is CVE-2026-27448 in the CISA KEV catalog?

No. CVE-2026-27448 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-27448?

CVE-2026-27448 has a CVSS v3 base score of 5.3 (Low).

What is the EPSS score for CVE-2026-27448?

CVE-2026-27448 has an EPSS score of 0.24% (15th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-27448?

Upgrade pyopenssl on debian unstable to 26.0.0-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2026-27448

LOW

5.3

CVSS v3

NVD

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.

CWE-636

How to fix

Remediation Available

pyopensslDebian

Fixed in:26.0.0-1CVE-2026-27448

pyopensslUbuntu

Fixed in:0.15.1-2ubuntu0.2+esm1USN-8335-1

Fixed in:17.5.0-1ubuntu1+esm1USN-8335-1

Fixed in:19.0.0-1ubuntu0.1~esm1USN-8335-1

Fixed in:21.0.0-1ubuntu0.1USN-8115-1

Fixed in:23.2.0-1ubuntu0.1USN-8115-1

Fixed in:25.0.0-1ubuntu0.1USN-8115-1

python-opensslUbuntu

Fixed in:0.15.1-2ubuntu0.2+esm1USN-8335-1

Fixed in:17.5.0-1ubuntu1+esm1USN-8335-1

Fixed in:19.0.0-1ubuntu0.1~esm1USN-8335-1

python3-opensslUbuntu

Fixed in:0.15.1-2ubuntu0.2+esm1USN-8335-1

Fixed in:17.5.0-1ubuntu1+esm1USN-8335-1

Fixed in:19.0.0-1ubuntu0.1~esm1USN-8335-1

Fixed in:21.0.0-1ubuntu0.1USN-8115-1

Fixed in:23.2.0-1ubuntu0.1USN-8115-1

Fixed in:25.0.0-1ubuntu0.1USN-8115-1

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

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.24%probability of exploitation in 30 days

15thpercentile

Low risk: more likely to be exploited than 15% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Release Notes1

github.com

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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.