{"id":"CVE-2026-111749","kind":"vulnerability","aliases":["CVE-2026-111749","GHSA-gx76-c99x-2c96"],"related":[],"title":"AIOHTTP: Cookie from subdomain can remove Host-Only Scope from existing cookies","description":"AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, Host-Only scope on an existing parent-domain cookie can be removed by a subdomain. A user who accesses an untrusted subdomain can consequently have host-only protections stripped from cookies, although impact is limited when applications do not reflect those cookies to a browser. This issue is fixed in version 3.14.4.","summary":"AIOHTTP's cookie jar lets a subdomain remove the Host-Only flag from an existing cookie set for a parent domain, so the cookie becomes sent to the parent domain and its other subdomains. An attacker controlling a subdomain can strip that protection from cookies held by a client using the library.","severity":"low","cvss":2.3,"epss":0.002940000034868717,"exploited":false,"exploited_at":null,"products":[{"name":"aiohttp","fixed":["3.14.4"],"affected":"<= 3.14.3","ecosystem":"pypi"}],"ecosystems":["pypi"],"tags":["aiohttp","cookie-handling","cwe-565","package","python"],"not_affected_if":["aiohttp-4.14.4-or-later","no-untrusted-subdomains","static-export"],"how_to_check":"Check whether the project pins aiohttp with pip show aiohttp or pip freeze | grep -i aiohttp and whether the version is 3.14.3 or lower.","fix":"Upgrade aiohttp to 3.14.4 or later.","status":"open","published_at":"2026-10-19T17:17:04+00:00","first_seen_at":"2026-10-23T19:11:32+00:00","triaged_at":"2026-10-23T20:13:27+00:00","updated_at":"2026-10-23T21:57:18+00:00","category":"package","confidence":0.8,"triage":{"at":"2026-10-23T20:13:27Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade aiohttp to 3.14.4 or later.\nunknown","summary":"AIOHTTP's cookie jar lets a subdomain remove the Host-Only flag from an existing cookie set for a parent domain, so the cookie becomes sent to the parent domain and its other subdomains. An attacker controlling a subdomain can strip that protection from cookies held by a client using the library.","category":"package","who_cares":["python","aiohttp","cookie-handling"],"confidence":0.8,"analyst_note":"","how_to_check":"Check whether the project pins aiohttp with pip show aiohttp or pip freeze | grep -i aiohttp and whether the version is 3.14.3 or lower.\nunknown","needs_analyst":false,"not_affected_if":["aiohttp-4.14.4-or-later","no-untrusted-subdomains","static-export"],"severity_if_unknown":"low"},"cost_usd":0.000364,"input_tokens":2060,"output_tokens":316,"severity_before":"low"},"analyst_status":null,"analyst_note":null,"search":"'-111749':16A,24A '-2026':15A,23A '-565':31B '2c96':21A '3.14.4':100C,155C 'access':121C 'aiohttp':1A,25A,26B,34B,87C 'although':135C 'applic':140C 'asynchron':90C 'asyncio':95C 'attack':70B 'becom':59B 'browser':148C 'c99x':20A 'client':83B 'client/server':92C 'consequ':126C 'control':71B 'cooki':2A,13A,28B,36B,50B,58B,79B,111C,134C,145C 'cookie-handl':27B 'cve':14A,22A 'cwe':30B 'domain':55B,64B,110C 'exist':12A,49B,107C 'fix':152C 'flag':46B 'framework':93C 'ghsa':18A 'ghsa-gx76-c99x-2c96':17A 'gx76':19A 'handl':29B 'held':80B 'host':8A,44B,102C,129C 'host-on':7A,43B,101C,128C 'http':91C 'impact':136C 'issu':150C 'jar':37B 'let':38B 'librari':86B 'limit':138C 'packag':32B 'parent':54B,63B,109C 'parent-domain':108C 'prior':98C 'protect':77B,131C 'python':33B,97C 'reflect':143C 'remov':6A,41B,114C 'scope':10A,104C 'sent':60B 'set':51B 'strip':75B,132C 'subdomain':4A,40B,68B,73B,117C,124C 'untrust':123C 'use':84B 'user':119C 'version':154C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-19T17:17:04+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"ghsa","external_id":"GHSA-gx76-c99x-2c96","url":"https://github.com/advisories/GHSA-gx76-c99x-2c96","severity":"low","published_at":"2026-10-20T19:58:14+00:00","modified_at":"2026-10-20T19:58:15+00:00","first_seen_at":"2026-10-23T19:11:32+00:00","fetched_at":"2026-10-23T19:11:32+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-111749","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111749","severity":null,"published_at":"2026-10-19T17:17:04+00:00","modified_at":"2026-10-22T21:17:14+00:00","first_seen_at":"2026-10-23T21:57:18+00:00","fetched_at":"2026-10-23T22:28:57+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"}