CVE-2026-6019 | Python CPython up to 3.14.x HTML Parser http.cookies.Morsel.js_output control sequence (ID 90309)

VDB-359054 · CVE-2026-6019 · ID 90309 PYTHON CPYTHON UP TO 3.14.X HTML PARSER HTTP.COOKIES.MORSEL.JS_OUTPUT CONTROL SEQUENCE HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.5 $0-$5k 2.76+ Summaryinfo A vulnerability labeled as problematic has been found in Python CPython up to 3.14.x. This vulnerability affects the function http.cookies.Morsel.js_output of the component HTML Parser. Such manipulation leads to control sequence. This vulnerability is traded as CVE-2026-6019. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded. Detailsinfo A vulnerability was found in Python CPython up to 3.14.x. It has been rated as problematic. Affected by this issue is the function http.cookies.Morsel.js_output of the component HTML Parser. The manipulation with an unknown input leads to a control sequence vulnerability. Using CWE to declare the problem leads to CWE-150. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component. Impacted is confidentiality, integrity, and availability. CVE summarizes: http.cookies.Morsel.js_output() returns an inline snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value. The advisory is available at github.com. This vulnerability is handled as CVE-2026-6019 since 04/09/2026. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are needed for exploitation. Technical details are known, but there is no available exploit. Upgrading to version 3.15.0 eliminates this vulnerability. Applying the patch 76b3923d688c0efc580658476c5f525ec8735104 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. Productinfo Type Programming Language Software Vendor Python Name CPython Version 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 License open-source Website Product: https://github.com/python/cpython/ 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: 4.7 VulDB Meta Temp Score: 4.5 VulDB Base Score: 4.7 VulDB Temp Score: 4.5 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Control sequence CWE: CWE-150 / CWE-20 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: CPython 3.15.0 Patch: 76b3923d688c0efc580658476c5f525ec8735104 Timelineinfo 04/09/2026 CVE reserved 04/22/2026 +13 days Advisory disclosed 04/22/2026 +0 days VulDB entry created 04/22/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: 90309 Status: Confirmed CVE: CVE-2026-6019 (🔒) GCVE (CVE): GCVE-0-2026-6019 GCVE (VulDB): GCVE-100-359054 Entryinfo Created: 04/22/2026 22:27 Changes: 04/22/2026 22:27 (71) Complete: 🔍 Cache ID: 99:3D7:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸