Security update for python-tornado SUSE Patch security@suse.de SUSE Security Team SUSE-SU-2026:0623-1 Final 1 1 2026-02-25T09:15:12Z current 2026-02-25T09:15:12Z 2026-02-25T09:15:12Z cve-database/bin/generate-cvrf.pl 2017-02-24T01:00:00Z Security update for python-tornado This update for python-tornado fixes the following issues: - CVE-2025-67725: inefficient algorithm when parsing parameters for HTTP header values (bsc#1254905). - CVE-2025-67726: Denial of Service (DoS) via maliciously crafted HTTP request caused by the HTTPHeaders.add method (bsc#1254904). The CVRF data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0). SUSE-2026-623,SUSE-SLE-Manager-Tools-12-2026-623 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-20260623-1/ Link for SUSE-SU-2026:0623-1 https://lists.suse.com/pipermail/sle-security-updates/2026-February/024396.html E-Mail link for SUSE-SU-2026:0623-1 https://www.suse.com/support/security/rating/ SUSE Security Ratings https://bugzilla.suse.com/1254904 SUSE Bug 1254904 https://bugzilla.suse.com/1254905 SUSE Bug 1254905 https://www.suse.com/security/cve/CVE-2025-67725/ SUSE CVE CVE-2025-67725 page https://www.suse.com/security/cve/CVE-2025-67726/ SUSE CVE CVE-2025-67726 page SUSE Manager Client Tools 12 python-tornado-4.2.1-17.13.1 python3-tornado-4.2.1-17.13.1 python-tornado-4.2.1-17.13.1 as a component of SUSE Manager Client Tools 12 python3-tornado-4.2.1-17.13.1 as a component of SUSE Manager Client Tools 12 Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, a single maliciously crafted HTTP request can block the server's event loop for an extended period, caused by the HTTPHeaders.add method. The function accumulates values using string concatenation when the same header name is repeated, causing a Denial of Service (DoS). Due to Python string immutability, each concatenation copies the entire string, resulting in O(n^2) time complexity. The severity can vary from high if max_header_size has been increased from its default, to low if it has its default value of 64KB. This issue is fixed in version 6.5.3. CVE-2025-67725 SUSE Manager Client Tools 12:python-tornado-4.2.1-17.13.1 SUSE Manager Client Tools 12:python3-tornado-4.2.1-17.13.1 important 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-20260623-1/ https://www.suse.com/security/cve/CVE-2025-67725.html CVE-2025-67725 https://bugzilla.suse.com/1254905 SUSE Bug 1254905 Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n^2)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3. CVE-2025-67726 SUSE Manager Client Tools 12:python-tornado-4.2.1-17.13.1 SUSE Manager Client Tools 12:python3-tornado-4.2.1-17.13.1 important 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-20260623-1/ https://www.suse.com/security/cve/CVE-2025-67726.html CVE-2025-67726 https://bugzilla.suse.com/1254904 SUSE Bug 1254904