{"id":"CVE-2026-19048","kind":"vulnerability","aliases":["CVE-2026-19048"],"related":[],"title":"Synology DSM: thumbnail component follows links, lets users write arbitrary files","description":"An improper link resolution before file access vulnerability in the thumb in Synology DiskStation Manager (DSM) before 7.3.2-86009-5 and 7.4.1-90080-1 allows remote authenticated users to write arbitrary files and conduct denial-of-service attacks.","summary":"An improper link resolution flaw in the thumbnail component of Synology DiskStation Manager lets a logged-in user write files to arbitrary locations and crash the service. The sources rate it high severity (CVSS 8.1) but report no active exploitation.","severity":"high","cvss":8.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dsm","infrastructure","nas","self-hosted","synology"],"not_affected_if":["fixed-dsm-version","no-authenticated-users"],"how_to_check":"- Check the DSM version under Control Panel > Info Center; `unknown` for the exact command\n- Compare the installed version against the fixed releases listed in the fix field","fix":"- Synology DSM `7.3.2-86009-5` or later on the 7.3.2 branch\n- Synology DSM `7.4.1-90080-1` or later on the 7.4.1 branch","status":"open","published_at":"2026-11-12T04:17:19+00:00","first_seen_at":"2026-11-12T04:47:09+00:00","triaged_at":"2026-11-12T04:47:41+00:00","updated_at":"2026-11-12T04:47:41+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-11-12T04:47:41Z","model":"claude-haiku-5-5","output":{"fix":"- Synology DSM `7.3.2-86009-5` or later on the 7.3.2 branch\n- Synology DSM `7.4.1-90080-1` or later on the 7.4.1 branch","reach":"network","title":"Synology DSM: thumbnail component follows links, lets users write arbitrary files","impact":"high","summary":"An improper link resolution flaw in the thumbnail component of Synology DiskStation Manager lets a logged-in user write files to arbitrary locations and crash the service. The sources rate it high severity (CVSS 8.1) but report no active exploitation.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["synology","dsm","self-hosted","nas"],"confidence":0.7,"fix_status":"available","needs_auth":"yes","worst_case":"authenticated user writes arbitrary files and disrupts the NAS service","analyst_note":"Confirm which DSM feature the thumb component belongs to and whether it is enabled by default, using the Synology security advisory.","how_to_check":"- Check the DSM version under Control Panel > Info Center; `unknown` for the exact command\n- Compare the installed version against the fixed releases listed in the fix field","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["fixed-dsm-version","no-authenticated-users"],"who_is_affected":"Only Synology DiskStation Manager systems where a user has a valid account can reach the thumbnail component. Systems running a fixed DSM build on each branch, or with no untrusted accounts, are less exposed. The sources do not name the exact thumbnail feature or its default settings.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000755,"input_tokens":4547,"output_tokens":600,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-1':89C '-19048':14A,17A '-2026':13A,16A '-5':85C '-86009':84C '-90080':88C '7.3.2':83C '7.4.1':87C '8.1':60B 'access':72C 'activ':64B 'allow':90C 'arbitrari':10A,47B,96C 'attack':104C 'authent':92C 'compon':4A,33B 'conduct':99C 'crash':50B 'cve':12A,15A 'cvss':59B 'denial':101C 'denial-of-servic':100C 'diskstat':36B,79C 'dsm':2A,18B,81C 'exploit':65B 'file':11A,45B,71C,97C 'flaw':29B 'follow':5A 'high':57B 'host':23B 'improp':26B,67C 'infrastructur':19B 'let':7A,38B 'link':6A,27B,68C 'locat':48B 'log':41B 'logged-in':40B 'manag':37B,80C 'nas':20B 'rate':55B 'remot':91C 'report':62B 'resolut':28B,69C 'self':22B 'self-host':21B 'servic':52B,103C 'sever':58B 'sourc':54B 'synolog':1A,24B,35B,78C 'thumb':76C 'thumbnail':3A,32B 'user':8A,43B,93C 'vulner':73C 'write':9A,44B,95C","nicknames":[],"mitigations":[],"who_affected":"Only Synology DiskStation Manager systems where a user has a valid account can reach the thumbnail component. Systems running a fixed DSM build on each branch, or with no untrusted accounts, are less exposed. The sources do not name the exact thumbnail feature or its default settings.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dsm","high","infrastructure","nas","selfhosted","synology"],"campaign_type":null,"search_a":"'-19048':14A,17A '-2026':13A,16A 'arbitrari':10A 'compon':4A 'cve':12A,15A 'dsm':2A 'file':11A 'follow':5A 'let':7A 'link':6A 'synolog':1A 'thumbnail':3A 'user':8A 'write':9A","search_b":"'8.1':60B 'activ':64B 'arbitrari':47B 'compon':33B 'crash':50B 'cvss':59B 'diskstat':36B 'dsm':18B 'exploit':65B 'file':45B 'flaw':29B 'high':57B 'host':23B 'improp':26B 'infrastructur':19B 'let':38B 'link':27B 'locat':48B 'log':41B 'logged-in':40B 'manag':37B 'nas':20B 'rate':55B 'report':62B 'resolut':28B 'self':22B 'self-host':21B 'servic':52B 'sever':58B 'sourc':54B 'synolog':24B,35B 'thumbnail':32B 'user':43B 'write':44B","search_c":"'-1':89C '-5':85C '-86009':84C '-90080':88C '7.3.2':83C '7.4.1':87C 'access':72C 'allow':90C 'arbitrari':96C 'attack':104C 'authent':92C 'conduct':99C 'denial':101C 'denial-of-servic':100C 'diskstat':79C 'dsm':81C 'file':71C,97C 'improp':67C 'link':68C 'manag':80C 'remot':91C 'resolut':69C 'servic':103C 'synolog':78C 'thumb':76C 'user':93C 'vulner':73C 'write':95C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-12T04:17:19+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","cvss_by":"security@synology.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-19048","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19048","severity":null,"published_at":"2026-11-12T04:17:19+00:00","modified_at":"2026-11-12T04:17:19+00:00","first_seen_at":"2026-11-12T04:47:09+00:00","fetched_at":"2026-11-12T04:47:09+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}