{"id":"CVE-2026-82397","title":"Tornado is a Python web framework and asynchronous networking library","summary":"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. Reques…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-1284","CWE-1050"],"vendor":"tornado","product":"tornado","affected":["tornado <= 6.5.7"],"patched":["tornado 6.5.8"],"published":"2026-08-31","updated":"2026-09-09","sourceUpdated":"2026-09-09T21:09:13.080","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-82397","references":[{"url":"https://github.com/tornadoweb/tornado/commit/8d6363ed7b69d5f0da806efe34d256627a2191de","label":"security-advisories@github.com"},{"url":"https://github.com/tornadoweb/tornado/pull/3704","label":"security-advisories@github.com"},{"url":"https://github.com/tornadoweb/tornado/releases/tag/v6.5.8","label":"security-advisories@github.com"},{"url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4","label":"security-advisories@github.com"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82397"},{"url":"https://github.com/advisories/GHSA-mpf4-983q-p7j4"},{"url":"https://github.com/tornadoweb/tornado"},{"url":"https://pypi.org/project/tornado"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-82397.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-82397"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2526562"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-82397"},{"url":"https://access.redhat.com/errata/RHSA-2026:67147"},{"url":"https://access.redhat.com/errata/RHSA-2026:67146"},{"url":"https://access.redhat.com/errata/RHSA-2026:84798"},{"url":"https://access.redhat.com/errata/RHSA-2026:84843"},{"url":"https://access.redhat.com/errata/RHSA-2026:84844"},{"url":"https://access.redhat.com/errata/RHSA-2026:84734"}],"tags":["nvd","ghsa","pip","osv","csaf","vex","red-hat"],"epss":0.00346,"epssPercentile":0.27982,"aliases":["GHSA-mpf4-983q-p7j4","PYSEC-2026-3928"],"ecosystem":"pip","ingestedAt":"2026-09-02T14:45:29.925Z","slug":"CVE-2026-82397","body":"## Overview\n\nTornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-82397)\n\nAffected packages:\n\n- `tornado <= 6.5.7`\n\nPatched in:\n\n- `tornado 6.5.8`\n\nSource: https://github.com/advisories/GHSA-mpf4-983q-p7j4\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI), … · no fix planned: OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, Lightspeed Core, Red Hat Ansible Automation Platform 2, … · updated 2026-10-19 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-82397.json)\n- **RHSA-2026:67147** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67147)\n- **RHSA-2026:67146** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:67146)\n- **RHSA-2026:84798** · Red Hat · fixed in: Red Hat Enterprise Linux HighAvailability (v. 8), Red Hat Enterprise Linux ResilientStorage (v. 8) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84798)\n- **RHSA-2026:84843** · Red Hat · fixed in: Red Hat Enterprise Linux High Availability AUS (v.8.4), Red Hat Enterprise Linux HighAvailability EUS EXTENSION (v.8.4) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84843)\n- **RHSA-2026:84844** · Red Hat · fixed in: Red Hat Enterprise Linux High Availability E4S (v.8.8), Red Hat Enterprise Linux High Availability TUS (v.8.8) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84844)\n- **RHSA-2026:84734** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84734)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}