{"id":"CVE-2026-101356","kind":"vulnerability","aliases":["CVE-2026-101356"],"related":[],"title":"Apache Tomcat: HTTP/2 async servlets can mix up responses between users","description":"Incorrect object recycling and re-use vulnerability in Apache Tomcat affecting HTTP/2 processing of asynchronous servlets can trigger request and/or response mix-up between users.\n\n\n\nThis issue affects Apache Tomcat: from 11.0.22 through 11.0.26, from 10.1.55 through 10.1.60, from 9.0.118 through 9.0.122.\n\n\n\nUsers are recommended to upgrade to version 11.0.27, 10.1.61 or 9.0.123, which fixes the issue.","summary":"Apache Tomcat mishandles object recycling in HTTP/2 processing of asynchronous servlets, so requests and responses can get mixed up between users. An attacker may receive another user's response or have their request answered with someone else's data.","severity":"critical","cvss":9.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["http2","java","package","runtime","self-hosted","tomcat"],"not_affected_if":["default-config"],"how_to_check":"Check the Tomcat version: run catalina.sh version and look for 11.0.22 to 11.0.26, 10.1.55 to 10.1.60, or 9.0.118 to 9.0.122.","fix":"Upgrade to Tomcat 11.0.27, 10.1.61, or 9.0.123 or later.","status":"open","published_at":"2026-10-20T14:16:55+00:00","first_seen_at":"2026-10-23T21:57:20+00:00","triaged_at":"2026-10-23T22:39:31+00:00","updated_at":"2026-10-23T22:39:31+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-23T22:39:31Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade to Tomcat 11.0.27, 10.1.61, or 9.0.123 or later.","reach":"internet","title":"Apache Tomcat: HTTP/2 async servlets can mix up responses between users","impact":"high","summary":"Apache Tomcat mishandles object recycling in HTTP/2 processing of asynchronous servlets, so requests and responses can get mixed up between users. An attacker may receive another user's response or have their request answered with someone else's data.","category":"runtime","who_cares":["tomcat","java","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"Responses from one user's session delivered to another user","analyst_note":"","how_to_check":"Check the Tomcat version: run catalina.sh version and look for 11.0.22 to 11.0.26, 10.1.55 to 10.1.60, or 9.0.118 to 9.0.122.","needs_analyst":false,"not_affected_if":["default-config"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.00049,"input_tokens":3007,"output_tokens":378,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-101356':14A,17A '-2026':13A,16A '10.1.55':102C '10.1.60':104C '10.1.61':117C '11.0.22':98C '11.0.26':100C '11.0.27':116C '9.0.118':106C '9.0.122':108C '9.0.123':119C 'affect':76C,94C 'and/or':85C 'anoth':51B 'answer':59B 'apach':1A,26B,74C,95C 'async':4A 'asynchron':35B,80C 'attack':48B 'cve':12A,15A 'data':64B 'els':62B 'fix':121C 'get':42B 'host':24B 'http/2':3A,32B,77C 'http2':18B 'incorrect':65C 'issu':93C,123C 'java':19B 'may':49B 'mishandl':28B 'mix':7A,43B,88C 'mix-up':87C 'object':29B,66C 'packag':20B 'process':33B,78C 're':70C 're-us':69C 'receiv':50B 'recommend':111C 'recycl':30B,67C 'request':38B,58B,84C 'respons':9A,40B,54B,86C 'runtim':21B 'self':23B 'self-host':22B 'servlet':5A,36B,81C 'someon':61B 'tomcat':2A,25B,27B,75C,96C 'trigger':83C 'upgrad':113C 'use':71C 'user':11A,46B,52B,91C,109C 'version':115C 'vulner':72C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-20T14:16:55+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","cvss_by":"134c704f-9b21-4f2e-91b3-4a467353bcc0","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-101356","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-101356","severity":null,"published_at":"2026-10-20T14:16:55+00:00","modified_at":"2026-10-20T19:35:38+00:00","first_seen_at":"2026-10-23T21:57:20+00:00","fetched_at":"2026-10-23T22:28:58+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}