{"id":"CVE-2026-49854","summary":"Tornado: Out-of-bounds memory access in C extension","details":"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.","aliases":["GHSA-cx3h-4qpv-8hc9","PYSEC-2026-3388"],"modified":"2026-07-17T03:41:56.251346448Z","published":"2026-07-14T20:43:03.977Z","related":["CGA-gxmj-xx3h-94hw","SUSE-SU-2026:22286-1","SUSE-SU-2026:22373-1","SUSE-SU-2026:22430-1","SUSE-SU-2026:22445-1","SUSE-SU-2026:2725-1","SUSE-SU-2026:2726-1","openSUSE-SU-2026:11027-1","openSUSE-SU-2026:21067-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-126"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49854.json"},"references":[{"type":"WEB","url":"https://github.com/tornadoweb/tornado/releases/tag/v6.5.6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49854.json"},{"type":"ADVISORY","url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49854"},{"type":"FIX","url":"https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac"},{"type":"FIX","url":"https://github.com/tornadoweb/tornado/pull/3626"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/tornadoweb/tornado","events":[{"introduced":"0"},{"fixed":"96dc88c2a05705287856b2cd6b4b4034f9a6aaac"},{"fixed":"aba2569f7ed7a6bdbef816658fb6b7182531b751"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"6.5.6"}]}}],"versions":["v6.5.5","v6.5.4","v6.5.3","v6.5.2","v6.5.1","v6.5.0","v6.5.0b1","v6.4.1","v6.4.0","v6.4.0b1","v6.3.1","v6.3.0","v6.3.0b1","v6.2.0","v6.2.0b2","v6.2.0b1","v6.1.0","v6.1.0b2","v6.1.0b1","v6.0.0","v6.0.0b1","v5.1.0","v5.0.0","v4.5.0","v4.5.1","v4.4.1","v4.4.0","v4.4.0b1","v4.3.0","v4.3.0b2","v4.3.0b1","v4.2.0","v4.2.0b1","v4.1.0","v4.1.0b2","v4.1.0b1","v4.0.0","v4.0.0b3","v4.0.0b2","v4.0.0b1","v3.2.0","v3.2.0b2","v3.2.0b1","v3.1.0","v3.0.1","v3.0.0","v2.1.1","v2.3.0","v2.2.0","v2.1.0","v2.0.0","v1.2.0","v1.1.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49854.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}