{"id":"CVE-2026-11854","kind":"vulnerability","aliases":["CVE-2026-11854"],"related":[],"title":"Authentication endpoint error page reflects request data, enabling browser script injection","description":"The authentication endpoint generates an error message that includes reflected data directly from the request without sufficient sanitization or encoding. This allows an attacker to inject malicious scripts that can be executed in the context of a victim's browser.\n\nSuccessful exploitation enables an attacker to perform actions within the user's browser, such as redirecting the user to a malicious website, modifying the web page's user interface, or retrieving information. However, due to the httpOnly flag on session-related cookies, session hijacking or similar attacks are not possible.","summary":"The authentication endpoint places unsanitized request data into its error message, so an attacker can inject script that runs in a victim's browser. Per the description, session cookies are httpOnly, so session hijacking is not possible, but the script can redirect users, alter the page, or read information shown on it.","severity":"medium","cvss":6.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["other","web-apps"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-10-28T20:17:22+00:00","first_seen_at":"2026-10-28T20:35:10+00:00","triaged_at":"2026-10-28T20:36:15+00:00","updated_at":"2026-10-28T20:36:15+00:00","category":"other","confidence":0.4,"triage":{"at":"2026-10-28T20:36:15Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"internet","title":"Authentication endpoint error page reflects request data, enabling browser script injection","impact":"medium","summary":"The authentication endpoint places unsanitized request data into its error message, so an attacker can inject script that runs in a victim's browser. Per the description, session cookies are httpOnly, so session hijacking is not possible, but the script can redirect users, alter the page, or read information shown on it.","category":"other","nicknames":[],"who_cares":["web-apps"],"confidence":0.4,"needs_auth":"unknown","worst_case":"Injected script runs in victim browsers and can read visible page data","analyst_note":"Identify the affected product and versions from the NVD entry at https://nvd.nist.gov/vuln/detail/CVE-2026-11854; the sources do not name the product.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":[],"who_is_affected":"unknown","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000519,"input_tokens":3372,"output_tokens":364,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-11854':14A,17A '-2026':13A,16A 'action':119C 'allow':93C 'alter':65B 'app':21B 'attack':35B,95C,116C,159C 'authent':1A,23B,73C 'browser':9A,45B,111C,124C 'context':106C 'cooki':50B,154C 'cve':12A,15A 'data':7A,28B,82C 'descript':48B 'direct':83C 'due':145C 'enabl':8A,114C 'encod':91C 'endpoint':2A,24B,74C 'error':3A,31B,77C 'execut':103C 'exploit':113C 'flag':149C 'generat':75C 'hijack':55B,156C 'howev':144C 'httpon':52B,148C 'includ':80C 'inform':70B,143C 'inject':11A,37B,97C 'interfac':140C 'malici':98C,132C 'messag':32B,78C 'modifi':134C 'page':4A,67B,137C 'per':46B 'perform':118C 'place':25B 'possibl':58B,162C 'read':69B 'redirect':63B,127C 'reflect':5A,81C 'relat':153C 'request':6A,27B,86C 'retriev':142C 'run':40B 'sanit':89C 'script':10A,38B,61B,99C 'session':49B,54B,152C,155C 'session-rel':151C 'shown':71B 'similar':158C 'success':112C 'suffici':88C 'unsanit':26B 'user':64B,122C,129C,139C 'victim':43B,109C 'web':20B,136C 'web-app':19B 'websit':133C 'within':120C 'without':87C","nicknames":[],"mitigations":[],"who_affected":null,"tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T20:17:22+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","cvss_by":"ed10eef1-636d-4fbe-9993-6890dfa878f8","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-11854","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-11854","severity":null,"published_at":"2026-10-28T20:17:22+00:00","modified_at":"2026-10-28T20:17:22+00:00","first_seen_at":"2026-10-28T20:35:10+00:00","fetched_at":"2026-10-28T20:35:10+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"}