{"id":"CVE-2026-119764","kind":"vulnerability","aliases":["CVE-2026-119764"],"related":[],"title":"Mythic C2 UI: planted HTML in PDF-named files steals operator logins","description":"Mythic 3.2.16 through 3.4.0.61 contains a stored cross-site scripting vulnerability that allows attackers controlling target endpoint files to run JavaScript in the Mythic UI origin by planting HTML in .pdf-named files. When an operator downloads the file and clicks Preview Media, content-sniffed HTML from /direct/view renders same-origin, stealing localStorage JWTs for full GraphQL and REST access.","summary":"Mythic, a command-and-control framework, has a stored cross-site scripting flaw in versions 3.2.16 through 3.4.0.61. An attacker who controls files on a target endpoint can plant HTML disguised as a PDF, and when an operator clicks Preview Media the script runs in the Mythic UI and reads localStorage JWTs, giving full GraphQL and REST access.","severity":"high","cvss":7.4,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Mythic","fixed":[],"affected":">= 3.2.16, <= 3.4.0.61","ecosystem":"other"}],"ecosystems":[],"tags":["c2-frameworks","mythic","other","red-team","self-hosted","xss"],"not_affected_if":["version-outside-range"],"how_to_check":"Run mythic-cli version (or check the Mythic release/tag you deployed) and compare to 3.2.16 through 3.4.0.61. If you are in the range, treat any file downloaded from an agent as untrusted and do not click Preview Media on it (it is served from /direct/view in the UI origin). A build that includes upstream commit f06b3ed2 should have the fix; confirm in the repo.","fix":"No fixed release confirmed. Upstream commit f06b3ed2d1de6577744cc0b3146966c625685859 is referenced by the advisory; update to a Mythic release containing it once published.","status":"open","published_at":"2026-10-30T18:17:27+00:00","first_seen_at":"2026-10-30T18:55:29+00:00","triaged_at":"2026-10-30T18:56:50+00:00","updated_at":"2026-10-30T18:58:15+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-10-30T18:56:50Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Mythic C2 UI: planted HTML in PDF-named files steals operator logins","impact":"high","summary":"Mythic, a command-and-control framework, has a stored cross-site scripting flaw in versions 3.2.16 through 3.4.0.61. An attacker who controls files on a target endpoint can plant HTML disguised as a PDF, and when an operator clicks Preview Media the script runs in the Mythic UI and reads localStorage JWTs, giving full GraphQL and REST access.","audience":"developers","category":"other","nicknames":[],"who_cares":["mythic","c2-frameworks","red-team"],"confidence":0.6,"fix_status":"unknown","needs_auth":"unknown","worst_case":"Attacker takes over the Mythic UI session and full API access","analyst_note":"Check the NVD entry and the Mythic project for a fixed version and whether the fix is released; the sources do not state one.","how_to_check":"- Check the installed Mythic version against the affected range `3.2.16` through `3.4.0.61`\n- Look for a `/direct/view` route serving uploaded files in the Mythic UI origin (unknown if the sources give a file path)","plain_action":"","needs_analyst":true,"not_affected_if":["version-outside-range"],"who_is_affected":"Teams running Mythic in the affected version range, where operators preview media collected from target endpoints. The flaw needs an attacker-controlled file to reach an operator's preview, so teams on versions outside the range can skip it. The sources do not say which versions are patched.","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000709,"input_tokens":4181,"output_tokens":582,"severity_before":"high"},"analyst_status":"done","analyst_note":"Check the NVD entry and the Mythic project for a fixed version and whether the fix is released; the sources do not state one.","search":"'-119764':16A,19A '-2026':15A,18A '/direct/view':143C '3.2.16':50B,94C '3.4.0.61':52B,96C 'access':92B,156C 'allow':106C 'attack':54B,107C 'c2':2A,22B 'c2-frameworks':21B 'click':73B,135C 'command':36B 'command-and-control':35B 'contain':97C 'content':139C 'content-snif':138C 'control':38B,56B,108C 'cross':44B,101C 'cross-sit':43B,100C 'cve':14A,17A 'disguis':65B 'download':131C 'endpoint':61B,110C 'file':10A,57B,111C,127C,133C 'flaw':47B 'framework':23B,39B 'full':88B,152C 'give':87B 'graphql':89B,153C 'host':31B 'html':5A,64B,122C,141C 'javascript':114C 'jwts':86B,150C 'localstorag':85B,149C 'login':13A 'media':75B,137C 'mythic':1A,20A,24B,33B,81B,93C,117C 'name':9A,126C 'oper':12A,72B,130C 'origin':119C,147C 'pdf':8A,68B,125C 'pdf-name':7A,124C 'plant':4A,63B,121C 'preview':74B,136C 'read':84B 'red':27B 'red-team':26B 'render':144C 'rest':91B,155C 'run':78B,113C 'same-origin':145C 'script':46B,77B,103C 'self':30B 'self-host':29B 'site':45B,102C 'snif':140C 'steal':11A,148C 'store':42B,99C 'target':60B,109C 'team':28B 'ui':3A,82B,118C 'version':49B 'vulner':104C 'xss':32B","nicknames":[],"mitigations":[],"who_affected":"Teams running Mythic in the affected version range, where operators preview media collected from target endpoints. The flaw needs an attacker-controlled file to reach an operator's preview, so teams on versions outside the range can skip it. The sources do not say which versions are patched.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"developers","plain_action":null,"first_public_at":"2026-10-30T18:17:27+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/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":"disclosure@vulncheck.com","poc_count":1,"sources":[{"source":"nvd","external_id":"CVE-2026-119764","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119764","severity":null,"published_at":"2026-10-30T18:17:27+00:00","modified_at":"2026-10-30T18:17:27+00:00","first_seen_at":"2026-10-30T18:55:29+00:00","fetched_at":"2026-10-30T18:55:29+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-119764:1184","url":null,"severity":null,"published_at":"2026-10-30T18:58:15+00:00","modified_at":"2026-10-30T18:58:15+00:00","first_seen_at":"2026-10-30T18:58:15+00:00","fetched_at":"2026-10-30T18:58:15+00:00","note":"VulnCheck (CNA) advisory read: affected Mythic >=3.2.16 <=3.4.0.61, CWE-79, vulnerable code ResponseDisplayMedia.js L335-336, fix commit f06b3ed referenced and a public PoC repo h00die/mythic_xss linked, but I could not read either page, and no release with the fix is confirmed (releases page I got looked stale). Fixed version unknown; nothing verified."}],"documents":[{"id":25341,"url":"https://www.vulncheck.com/advisories/mythic-3.2.16-through-3.4.0.61-stored-xss-via-agent-downloaded-file-preview","title":"VulnCheck: Mythic 3.2.16 through 3.4.0.61 Stored XSS via Agent-Downloaded File Preview","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":25342,"url":"https://github.com/its-a-feature/Mythic/commit/f06b3ed2d1de6577744cc0b3146966c625685859","title":"Mythic commit f06b3ed (referenced by advisory; content not read)","kind":"other","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":25343,"url":"https://github.com/h00die/mythic_xss","title":"h00die/mythic_xss (referenced; not read)","kind":"poc","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"poc","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}