{"id":"CVE-2026-65637","kind":"vulnerability","aliases":["CVE-2026-65637","GHSA-f525-44xv-f2qj"],"related":[],"title":"Apache Tomcat - HTTP/2 no-authority bypass of strict SNI validation","description":"Improper Input Validation vulnerability in Apache Tomcat due to incomplete fix for CVE-2026-32990.\n\n\n\nThis issue affects Apache Tomcat: from 11.0.20 through 11.0.24, from 10.1.53 through 10.1.57, from 9.0.115 through 9.0.120.\n\n\n\nUsers are recommended to upgrade to version 11.0.25, 10.1.58 or 9.0.121, which fix the issue.","summary":"Apache Tomcat's HTTP/2 handling does not enforce strict SNI validation when a request has no authority header, an incomplete fix for CVE-2026-32990. The sources do not say what an attacker can reach or read after the bypass.","severity":"critical","cvss":9.8,"epss":0.00612,"exploited":false,"exploited_at":null,"products":[{"name":"org.apache.tomcat:tomcat-coyote","fixed":["11.0.25"],"affected":">= 11.0.20, < 11.0.25","ecosystem":"maven"},{"name":"org.apache.tomcat:tomcat-coyote","fixed":["10.1.59"],"affected":">= 10.1.53, <= 10.1.57","ecosystem":"maven"},{"name":"org.apache.tomcat:tomcat-coyote","fixed":["9.0.121"],"affected":">= 9.0.115, < 9.0.121","ecosystem":"maven"},{"name":"org.apache.tomcat.embed:tomcat-embed-core","fixed":["11.0.25"],"affected":">= 11.0.20, < 11.0.25","ecosystem":"maven"},{"name":"org.apache.tomcat.embed:tomcat-embed-core","fixed":["10.1.59"],"affected":">= 10.1.53, <= 10.1.57","ecosystem":"maven"},{"name":"org.apache.tomcat.embed:tomcat-embed-core","fixed":["9.0.121"],"affected":">= 9.0.115, < 9.0.121","ecosystem":"maven"},{"name":"apache tomcat","fixed":["9.0.121"],"affected":">= 9.0.115, < 9.0.121","ecosystem":"vendor"},{"name":"apache tomcat","fixed":["10.1.58"],"affected":">= 10.1.53, < 10.1.58","ecosystem":"vendor"},{"name":"apache tomcat","fixed":["11.0.25"],"affected":">= 11.0.20, < 11.0.25","ecosystem":"vendor"}],"ecosystems":["maven","vendor"],"tags":["cwe-20","java","maven","package","self-hosted","tomcat"],"not_affected_if":["default-config","http1-only"],"how_to_check":"- Run `mvn dependency:list | grep tomcat` or inspect the lib directory to find tomcat-coyote or tomcat-embed-core versions\n- Confirm the version is between `11.0.20` and `11.0.24`, `10.1.53` and `10.1.57`, or `9.0.115` and `9.0.120`\n- Check whether HTTP/2 is enabled on the connector","fix":"- Upgrade Tomcat 11.x to `11.0.25`\n- Upgrade Tomcat 10.1.x to `10.1.59`\n- Upgrade Tomcat 9.0.x to `9.0.121`","status":"open","published_at":"2026-08-25T22:17:05+00:00","first_seen_at":"2026-10-27T14:47:35+00:00","triaged_at":"2026-10-27T14:49:40+00:00","updated_at":"2026-10-27T15:02:22+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-27T14:49:40Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Tomcat 11.x to `11.0.25`\n- Upgrade Tomcat 10.1.x to `10.1.59`\n- Upgrade Tomcat 9.0.x to `9.0.121`","reach":"internet","title":"Apache Tomcat: HTTP/2 requests skip strict SNI host validation","impact":"medium","summary":"Apache Tomcat's HTTP/2 handling does not enforce strict SNI validation when a request has no authority header, an incomplete fix for CVE-2026-32990. The sources do not say what an attacker can reach or read after the bypass.","category":"package","nicknames":[],"who_cares":["java","tomcat","self-hosted","maven"],"confidence":0.6,"needs_auth":"unknown","worst_case":"unknown; SNI validation bypass may expose virtual-host routing","analyst_note":"Check the GHSA-f525-44xv-f2qj advisory and CVE-2026-32990 for what the SNI bypass lets an attacker reach, and whether HTTP/2 must be enabled.","how_to_check":"- Run `mvn dependency:list | grep tomcat` or inspect the lib directory to find tomcat-coyote or tomcat-embed-core versions\n- Confirm the version is between `11.0.20` and `11.0.24`, `10.1.53` and `10.1.57`, or `9.0.115` and `9.0.120`\n- Check whether HTTP/2 is enabled on the connector","needs_analyst":true,"not_affected_if":["default-config","http1-only"],"who_is_affected":"Servers running Apache Tomcat 9.0.115 to 9.0.120, 10.1.53 to 10.1.57, or 11.0.20 to 11.0.24 that accept HTTP/2 connections are in scope. Applications that use Tomcat only behind a proxy speaking HTTP/1.1, or that do not enable HTTP/2 on the connector, are likely less exposed, but the sources do not confirm this. Teams on the listed fixed versions can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000744,"input_tokens":3698,"output_tokens":748,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-20':57B '-2026':13A,21A,88B,118C '-32990':89B,119C '-65637':14A,22A '10.1.53':130C '10.1.57':132C '10.1.58':145C '11.0.20':126C '11.0.24':128C '11.0.25':144C '44xv':18A '9.0.115':134C '9.0.120':136C '9.0.121':147C 'affect':122C 'apach':1A,65B,110C,123C 'apache':50A,52A,54A 'attack':97B 'author':6A,81B 'bypass':7A,104B 'core':39A,44A,49A 'coyote':26A,30A,34A 'cve':12A,20A,87B,117C 'cwe':56B 'due':112C 'embed':38A,43A,48A 'enforc':72B 'f2qj':19A 'f525':17A 'fix':85B,115C,149C 'ghsa':16A 'ghsa-f525-44xv-f2qj':15A 'handl':69B 'header':82B 'host':63B 'http/2':3A,68B 'improp':105C 'incomplet':84B,114C 'input':106C 'issu':121C,151C 'java':58B 'maven':59B 'no-author':4A 'org.apache.tomcat':23A,27A,31A 'org.apache.tomcat.embed':35A,40A,45A 'packag':60B 'reach':99B 'read':101B 'recommend':139C 'request':78B 'say':94B 'self':62B 'self-host':61B 'sni':10A,74B 'sourc':91B 'strict':9A,73B 'tomcat':2A,25A,29A,33A,37A,42A,47A,51A,53A,55A,64B,66B,111C,124C 'tomcat-coyote':24A,28A,32A 'tomcat-embed-core':36A,41A,46A 'upgrad':141C 'user':137C 'valid':11A,75B,107C 'version':143C 'vulner':108C","nicknames":[],"mitigations":[],"who_affected":"Servers running Apache Tomcat 9.0.115 to 9.0.120, 10.1.53 to 10.1.57, or 11.0.20 to 11.0.24 that accept HTTP/2 connections are in scope. Applications that use Tomcat only behind a proxy speaking HTTP/1.1, or that do not enable HTTP/2 on the connector, are likely less exposed, but the sources do not confirm this. Teams on the listed fixed versions can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-08-25T22:17:05+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"GitHub","poc_count":0,"sources":[{"source":"ghsa","external_id":"GHSA-f525-44xv-f2qj","url":"https://github.com/advisories/GHSA-f525-44xv-f2qj","severity":"critical","published_at":"2026-08-26T00:30:52+00:00","modified_at":"2026-10-27T14:45:12+00:00","first_seen_at":"2026-10-27T14:47:35+00:00","fetched_at":"2026-10-27T14:47:35+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-65637","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65637","severity":null,"published_at":"2026-08-25T22:17:05+00:00","modified_at":"2026-08-27T15:19:42+00:00","first_seen_at":"2026-10-27T15:02:22+00:00","fetched_at":"2026-10-27T15:02:22+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"}