VDB-351397 · CVE-2026-27448 · GHSA-vp96-hxj8-p424

pyca pyOpenSSL up to 0.14.0/26.0.0 set_tlsext_servername_callback access control

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in pyca pyOpenSSL up to 0.14.0/26.0.0. This affects the function set_tlsext_servername_callback. This manipulation causes access control. This vulnerability is tracked as CVE-2026-27448. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in pyca pyOpenSSL up to 0.14.0/26.0.0. Affected by this vulnerability is the function set_tlsext_servername_callback. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

This vulnerability is known as CVE-2026-27448. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 302891 (Linux Distros Unpatched Vulnerability : CVE-2026-27448), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 26.0.0 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch d41a814759a9fb49584ca8ab3f7295de49a85aa0 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (302891) and CERT Bund (WID-SEC-2026-1183). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • RESF Rocky Linux

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.3
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 302891
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-27448

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: pyOpenSSL 26.0.0
Patch: d41a814759a9fb49584ca8ab3f7295de49a85aa0

Timelineinfo

03/18/2026 Advisory disclosed
03/18/2026 +0 days VulDB entry created
06/10/2026 +84 days VulDB entry last update

Sourcesinfo

Product: github.com

Status: Confirmed

CVE: CVE-2026-27448 (🔒)
GCVE (CVE): GCVE-0-2026-27448
GCVE (VulDB): GCVE-100-351397
CERT Bund: WID-SEC-2026-1183 - Red Hat Hardened Images RPMs (jq und pyOpenSSL): Mehrere Schwachstellen

Entryinfo

Created: 03/18/2026 02:19
Updated: 06/10/2026 18:52
Changes: 03/18/2026 02:19 (58), 03/18/2026 21:55 (2), 03/21/2026 23:11 (15), 03/23/2026 20:28 (11), 04/22/2026 03:53 (7), 05/04/2026 00:37 (1), 06/10/2026 18:52 (1)
Complete: 🔍
Cache ID: 216::103

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