Security update for python-Flask SUSE Patch security@suse.de SUSE Security Team SUSE-SU-2026:0849-1 Final 1 1 2026-03-09T10:13:40Z current 2026-03-09T10:13:40Z 2026-03-09T10:13:40Z cve-database/bin/generate-cvrf.pl 2017-02-24T01:00:00Z Security update for python-Flask This update for python-Flask fixes the following issue: - CVE-2026-27205: information disclosure due to Flask session not adding the `Vary: Cookie` header (bsc#1258700). The CVRF data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0). SUSE-2026-849,SUSE-SLE-Module-Python3-15-SP7-2026-849,openSUSE-SLE-15.6-2026-849 Copyright SUSE LLC under the Creative Commons License 4.0 with Attribution (CC-BY-4.0) https://www.suse.com/support/update/announcement/2026/suse-su-20260849-1/ Link for SUSE-SU-2026:0849-1 https://lists.suse.com/pipermail/sle-security-updates/2026-March/024661.html E-Mail link for SUSE-SU-2026:0849-1 https://www.suse.com/support/security/rating/ SUSE Security Ratings https://bugzilla.suse.com/1258700 SUSE Bug 1258700 https://www.suse.com/security/cve/CVE-2026-27205/ SUSE CVE CVE-2026-27205 page SUSE Linux Enterprise Module for Python 3 15 SP7 openSUSE Leap 15.6 python311-Flask-2.3.2-150400.3.9.1 python311-Flask-doc-2.3.2-150400.3.9.1 python311-Flask-2.3.2-150400.3.9.1 as a component of SUSE Linux Enterprise Module for Python 3 15 SP7 python311-Flask-2.3.2-150400.3.9.1 as a component of openSUSE Leap 15.6 python311-Flask-doc-2.3.2-150400.3.9.1 as a component of openSUSE Leap 15.6 Flask is a web server gateway interface (WSGI) web application framework. In versions 3.1.2 and below, when the session object is accessed, Flask should set the Vary: Cookie header., resulting in a Use of Cache Containing Sensitive Information vulnerability. The logic instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked. The severity and risk depend on the application being hosted behind a caching proxy that doesn't ignore responses with cookies, not setting a Cache-Control header to mark pages as private or non-cacheable, and accessing the session in a way that only touches keys without reading values or mutating the session. The issue has been fixed in version 3.1.3. CVE-2026-27205 SUSE Linux Enterprise Module for Python 3 15 SP7:python311-Flask-2.3.2-150400.3.9.1 openSUSE Leap 15.6:python311-Flask-2.3.2-150400.3.9.1 openSUSE Leap 15.6:python311-Flask-doc-2.3.2-150400.3.9.1 moderate To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch". https://www.suse.com/support/update/announcement/2026/suse-su-20260849-1/ https://www.suse.com/security/cve/CVE-2026-27205.html CVE-2026-27205 https://bugzilla.suse.com/1258700 SUSE Bug 1258700