{"id":"CVE-2021-26829","kind":"vulnerability","aliases":["CVE-2021-26829"],"related":[],"title":"OpenPLC ScadaBR through 0.9.1 on Linux and through 1.12.4 on Windows allows stored XSS via system_settings.shtm","description":"OpenPLC ScadaBR contains a cross-site scripting vulnerability via system_settings.shtm.\n\nCISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","summary":"OpenPLC ScadaBR has a reflected or stored cross-site scripting flaw in its system_settings.shtm page. An attacker can run script in the browser of a logged-in user who opens a crafted page, which CISA lists as actively exploited.","severity":"medium","cvss":5.4,"epss":null,"exploited":true,"exploited_at":"2025-11-28T00:00:00+00:00","products":[{"name":"OpenPLC ScadaBR","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"scadabr","fixed":[],"affected":"<= 0.9.1","ecosystem":"vendor"},{"name":"scadabr","fixed":[],"affected":"<= 1.12.4","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","industrial-control","infrastructure","openplc","scadabr","self-hosted"],"not_affected_if":["not-running-scadabr"],"how_to_check":null,"fix":"Apply vendor mitigations per CISA guidance, or discontinue use of ScadaBR if no mitigation is available.","status":"open","published_at":"2021-06-11T12:15:12+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:44:17+00:00","updated_at":"2026-10-23T23:44:51+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-10-23T20:44:17Z","model":"claude-haiku-5-5","output":{"fix":"Apply vendor mitigations per CISA guidance, or discontinue use of ScadaBR if no mitigation is available.\nunknown","reach":"network","summary":"OpenPLC ScadaBR has a reflected or stored cross-site scripting flaw in its system_settings.shtm page. An attacker can run script in the browser of a logged-in user who opens a crafted page, which CISA lists as actively exploited.","category":"infrastructure","who_cares":["openplc","scadabr","industrial-control","self-hosted"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Attacker runs script in an operator's browser session and can act as that user.","analyst_note":"Find the affected and fixed ScadaBR versions and the vendor mitigation text; check the NVD or vendor advisory for the exact exposure.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["not-running-scadabr"],"user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"low"},"cost_usd":0.000435,"input_tokens":2527,"output_tokens":365,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-01':101C '-2021':18A,21A '-26829':19A,22A '0.9.1':4A '1.12.4':9A '22':100C 'action':91C 'activ':76B 'allow':12A 'appli':92C 'applic':98C 'attack':54B 'bod':99C 'browser':60B 'cisa':73B,89C 'cloud':104C 'contain':80C 'control':30B 'craft':70B 'cross':45B,83C 'cross-sit':44B,82C 'cve':17A,20A 'discontinu':107C 'exploit':27B,77B 'flaw':48B 'follow':97C 'guidanc':102C 'host':36B 'industri':29B 'industrial-control':28B 'infrastructur':31B 'instruct':96C 'linux':6A 'list':74B 'log':64B 'logged-in':63B 'mitig':93C,113C 'open':68B 'openplc':1A,23A,32B,37B,78C 'page':52B,71B 'per':94C 'product':111C 'reflect':41B 'requir':90C 'run':56B 'scadabr':2A,24A,25A,26A,33B,38B,79C 'script':47B,57B,85C 'self':35B 'self-host':34B 'servic':105C 'site':46B,84C 'store':13A,43B 'system_settings.shtm':16A,51B,88C 'unavail':115C 'use':108C 'user':66B 'vendor':95C 'via':15A,87C 'vulner':86C 'window':11A 'xss':14A","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-06-11T12:15:12+00:00","kev":{"dateAdded":"2025-11-28","dueDate":"2025-12-19","requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-26829","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-26829","severity":null,"published_at":"2025-11-28T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T13:39:29+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-26829","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-26829","severity":null,"published_at":"2021-06-11T12:15:12+00:00","modified_at":"2026-06-17T03:43:50+00:00","first_seen_at":"2026-10-23T23:44:51+00:00","fetched_at":"2026-10-23T23:44:51+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"}