{"id":"CVE-2026-91990","title":"Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit","summary":"Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create lar…","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-770"],"vendor":"tornadoweb","product":"tornado","affected":["tornado < 6.5.8"],"published":"2026-09-15","updated":"2026-09-16","sourceUpdated":"2026-09-16T13:42:49.167","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-91990","references":[{"url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/tornado-before-6.5.8-memory-amplification-dos-via-multipart","label":"disclosure@vulncheck.com"},{"url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://github.com/tornadoweb/tornado/pull/3704"},{"url":"https://github.com/tornadoweb/tornado/commit/de85b3f87446e323e881bbaa3d5a74f4b76e5f05"},{"url":"https://gist.github.com/afldl/649861f25d39b53b7edbe0298e171617"},{"url":"https://github.com/tornadoweb/tornado"},{"url":"https://github.com/tornadoweb/tornado/releases/tag/v6.5.8"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91990.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-91990"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2533953"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-91990"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91990"},{"url":"https://access.redhat.com/errata/RHSA-2026:79378"},{"url":"https://access.redhat.com/errata/RHSA-2026:80741"},{"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-2026:84734"}],"tags":["nvd","cve.org","exploit-available","osv","pip","csaf","vex","red-hat"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-15T16:04:53.956684Z"},"ingestedAt":"2026-09-15T15:39:12.909Z","aliases":["GHSA-8423-8fgw-73vq"],"ecosystem":"pip","patched":["tornado 6.5.8"],"epss":0.00424,"epssPercentile":0.36475,"slug":"CVE-2026-91990","body":"## Overview\n\nTornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-91990)\n\nAffected packages:\n\n- `tornado < 6.5.8`\n\nPatched in:\n\n- `tornado 6.5.8`\n\nSource: https://osv.dev/vulnerability/GHSA-8423-8fgw-73vq\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Exploit Intelligence, Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI), … · no fix planned: Exploit Intelligence, OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, Lightspeed Core, … · updated 2026-10-19 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-91990.json)\n- **RHSA-2026:79378** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.7 · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:79378)\n- **RHSA-2026:80741** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:80741)\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-2026:84734** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84734)","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":204290,"id":"CVE-2026-91990","ts":1789490448304,"field":"exploit_available","old":"false","new":"true"}]}