{"id":"CVE-2026-49855","state":"PUBLISHED","title":"tornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)","description":"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumulated decompressed chunks, allowing a malicious server accessed by SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request=True to consume effectively unlimited memory. This issue is fixed in version 6.5.6.","publishedAt":"2026-07-14T20:45:02.982Z","updatedAt":"2026-07-16T14:56:38.904Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["tornadoweb tornado"],"affected":[{"vendor":"tornadoweb","product":"tornado","versions":[{"version":"< 6.5.6","status":"affected"}]}],"references":["https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56","https://github.com/tornadoweb/tornado/pull/3626","https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff"],"weaknesses":["CWE-409"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/49xxx/CVE-2026-49855.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-49855","state":"PUBLISHED","datePublished":"2026-07-14T20:45:02.982Z","dateUpdated":"2026-07-16T14:56:38.904Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-01T22:03:19.640Z"},"containers":{"cna":{"title":"tornado AsyncHTTPClient accumulates decompressed chunks without size limit (gzip bomb)","descriptions":[{"lang":"en","value":"Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumulated decompressed chunks, allowing a malicious server accessed by SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request=True to consume effectively unlimited memory. This issue is fixed in version 6.5.6."}],"affected":[{"vendor":"tornadoweb","product":"tornado","versions":[{"version":"< 6.5.6","status":"affected"}]}],"references":[{"url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56","name":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-mgf9-4vpg-hj56","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/tornadoweb/tornado/pull/3626","name":"https://github.com/tornadoweb/tornado/pull/3626","tags":["x_refsource_MISC"]},{"url":"https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff","name":"https://github.com/tornadoweb/tornado/commit/ff808b33adc52d89a549376a5e3628e92abbc8ff","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-409","lang":"en","description":"CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-14T20:45:02.982Z"},"source":{"advisory":"GHSA-mgf9-4vpg-hj56","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-16T14:55:32.574509Z","id":"CVE-2026-49855","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-16T14:56:38.904Z"}}]}}}