{"id":"CVE-2026-39813","kind":"vulnerability","aliases":["CVE-2026-39813"],"related":[],"title":"Fortinet FortiSandbox: path traversal lets unauthenticated attackers read arbitrary files","description":"WAF Release - 2026-07-01 · Changelog\n\n# Changelog\n\nNew updates and improvements at Cloudflare.\n\nJuly 1, 2026\n\n## WAF Release - 2026-07-01\n\nThis release adds targeted coverage for a path traversal flaw in Fortinet FortiSandbox (CVE-2026-39813) and transitions the Anomaly:Header:User-Agent - Fake Bing or MSN Bot rule action from Block to Disabled.\n\nKey Findings\n\n- CVE-2026-39813: A path traversal vulnerability in Fortinet FortiSandbox allows remote, unauthenticated attackers to read arbitrary files from the underlying filesystem due to insufficient validation of user-supplied input paths.\n\n| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |\n| --- | --- | --- | --- | --- | --- | --- |\n| Cloudflare Managed Ruleset | ...d84c92c9 | N/A | Fortinet FortiSandbox - Path Traversal - CVE:CVE-2026-39813 | Log | Block | This is a new detection. |\n| Cloudflare Managed Ruleset | ...c12cf9c8 | N/A | Anomaly:Header:User-Agent - Fake Bing or MSN Bot | Enabled | Disabled | We are changing the action for this rule from BLOCK to Disabled |","summary":"FortiSandbox 4.4.0 through 4.4.8 and 5.0.0 through 5.0.5 contain a path traversal flaw in how user-supplied paths are validated. A remote attacker without an account can read arbitrary files from the appliance filesystem.","severity":"critical","cvss":9.8,"epss":0.0072,"exploited":false,"exploited_at":null,"products":[{"name":"fortinet fortisandbox","fixed":["4.4.9"],"affected":">= 4.4.0, < 4.4.9","ecosystem":"vendor"},{"name":"fortinet fortisandbox","fixed":["5.0.6"],"affected":">= 5.0.0, < 5.0.6","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["cloudflare","fortinet","fortisandbox","lab-disclosure","network","security-appliance","vendor"],"not_affected_if":["not-internet-exposed","patched-version"],"how_to_check":"- Check the FortiSandbox firmware version in the admin GUI or with `get system status` on the CLI.\n- Check whether the appliance is reachable from the internet or untrusted networks.\n- Review the Cloudflare changelog for WAF rule coverage if the appliance is behind Cloudflare.","fix":"- Upgrade FortiSandbox 4.4.x to `4.4.9`.\n- Upgrade FortiSandbox 5.0.x to `5.0.6`.\n- Restrict management and web access to trusted networks until patched.","status":"open","published_at":"2026-04-14T16:16:45+00:00","first_seen_at":"2026-10-24T18:43:45+00:00","triaged_at":"2026-10-25T05:27:57+00:00","updated_at":"2026-10-25T12:38:49+00:00","category":"vendor","confidence":0.8,"triage":{"at":"2026-10-25T05:27:57Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade FortiSandbox 4.4.x to `4.4.9`.\n- Upgrade FortiSandbox 5.0.x to `5.0.6`.\n- Restrict management and web access to trusted networks until patched.","reach":"network","title":"Fortinet FortiSandbox: path traversal lets unauthenticated attackers read arbitrary files","impact":"medium","summary":"FortiSandbox 4.4.0 through 4.4.8 and 5.0.0 through 5.0.5 contain a path traversal flaw in how user-supplied paths are validated. A remote attacker without an account can read arbitrary files from the appliance filesystem.","category":"vendor","nicknames":[],"who_cares":["fortisandbox","fortinet","security-appliance","network"],"confidence":0.8,"needs_auth":"no","worst_case":"Unauthenticated attacker reads arbitrary files from the appliance filesystem","analyst_note":"Confirm the exact affected version ranges and whether the vulnerable HTTP endpoint is enabled by default, using the Fortinet PSIRT advisory (not in the sources).","how_to_check":"- Check the FortiSandbox firmware version in the admin GUI or with `get system status` on the CLI.\n- Check whether the appliance is reachable from the internet or untrusted networks.\n- Review the Cloudflare changelog for WAF rule coverage if the appliance is behind Cloudflare.","needs_analyst":true,"not_affected_if":["patched-version","not-internet-exposed"],"who_is_affected":"FortiSandbox appliances on the affected 4.4.x and 5.0.x branches are exposed, since the flaw is reachable without authentication over the network. Appliances on fixed versions, or not reachable from untrusted networks, are lower risk. Cloudflare WAF customers have a managed rule, but that is not a substitute for patching.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000735,"input_tokens":3880,"output_tokens":694,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-01':71C,87C '-07':70C,86C '-2026':12A,15A,102C,126C,180C '-39813':13A,16A,103C,127C,181C '1':81C '2026':69C,82C,85C '4.4.0':33B '4.4.8':35B '5.0.0':37B '5.0.5':39B 'account':58B 'action':118C,165C,167C,210C 'add':90C 'agent':111C,198C 'allow':135C 'anomali':107C,194C 'applianc':30B,65B 'arbitrari':9A,61B,141C 'attack':7A,55B,138C 'bing':113C,200C 'block':120C,183C,215C 'bot':116C,203C 'c12cf9c8':192C 'chang':208C 'changelog':72C,73C 'cloudflar':21B,79C,169C,189C 'comment':168C 'contain':40B 'coverag':92C 'cve':11A,14A,101C,125C,178C,179C 'd84c92c9':172C 'descript':163C 'detect':188C 'disabl':122C,205C,217C 'disclosur':26B 'due':147C 'enabl':204C 'fake':112C,199C 'file':10A,62B,142C 'filesystem':66B,146C 'find':124C 'flaw':44B,97C 'fortinet':1A,17A,19A,22B,99C,133C,174C 'fortisandbox':2A,18A,20A,23B,32B,100C,134C,175C 'header':108C,195C 'id':159C,162C 'improv':77C 'input':155C 'insuffici':149C 'juli':80C 'key':123C 'lab':25B 'lab-disclosur':24B 'legaci':160C 'let':5A 'log':182C 'manag':170C,190C 'msn':115C,202C 'n/a':173C,193C 'network':27B 'new':74C,166C,187C 'path':3A,42B,50B,95C,129C,156C,176C 'previous':164C 'read':8A,60B,140C 'releas':68C,84C,89C 'remot':54B,136C 'rule':117C,158C,161C,213C 'ruleset':157C,171C,191C 'secur':29B 'security-appli':28B 'suppli':49B,154C 'target':91C 'transit':105C 'travers':4A,43B,96C,130C,177C 'unauthent':6A,137C 'under':145C 'updat':75C 'user':48B,110C,153C,197C 'user-ag':109C,196C 'user-suppli':47B,152C 'valid':52B,150C 'vendor':31B 'vulner':131C 'waf':67C,83C 'without':56B","nicknames":[],"mitigations":[],"who_affected":"FortiSandbox appliances on the affected 4.4.x and 5.0.x branches are exposed, since the flaw is reachable without authentication over the network. Appliances on fixed versions, or not reachable from untrusted networks, are lower risk. Cloudflare WAF customers have a managed rule, but that is not a substitute for patching.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-04-14T16:16:45+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"psirt@fortinet.com","poc_count":0,"sources":[{"source":"lab","external_id":"https://developers.cloudflare.com/changelog/post/2026-07-01-waf-release/#CVE-2026-39813","url":"https://developers.cloudflare.com/changelog/post/2026-07-01-waf-release/","severity":null,"published_at":"2026-07-01T18:42:49+00:00","modified_at":null,"first_seen_at":"2026-10-24T18:43:45+00:00","fetched_at":"2026-10-24T18:43:45+00:00","note":"Cloudflare: WAF Release - 2026-07-01 · Changelog"},{"source":"nvd","external_id":"CVE-2026-39813","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39813","severity":null,"published_at":"2026-04-14T16:16:45+00:00","modified_at":"2026-06-18T13:25:36+00:00","first_seen_at":"2026-10-24T18:53:56+00:00","fetched_at":"2026-10-24T18:53:56+00:00","note":null},{"source":"epss","external_id":"CVE-2026-39813","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-39813","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-25T12:38:49+00:00","fetched_at":"2026-10-25T12:38:49+00:00","note":null}],"documents":[{"id":2879,"url":"https://developers.cloudflare.com/changelog/post/2026-07-01-waf-release/","title":"Cloudflare: WAF Release - 2026-07-01 · Changelog","kind":"advisory","source":"lab","text":"WAF Release - 2026-07-01 · Changelog\n\n# Changelog\n\nNew updates and improvements at Cloudflare.\n\nJuly 1, 2026\n\n## WAF Release - 2026-07-01\n\nThis release adds targeted coverage for a path traversal flaw in Fortinet FortiSandbox (CVE-2026-39813) and transitions the Anomaly:Header:User-Agent - Fake Bing or MSN Bot rule action from Block to Disabled.\n\nKey Findings\n\n- CVE-2026-39813: A path traversal vulnerability in Fortinet FortiSandbox allows remote, unauthenticated attackers to read arbitrary files from the underlying filesystem due to insufficient validation of user-supplied input paths.\n\n| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |\n| --- | --- | --- | --- | --- | --- | --- |\n| Cloudflare Managed Ruleset | ...d84c92c9 | N/A | Fortinet FortiSandbox - Path Traversal - CVE:CVE-2026-39813 | Log | Block | This is a new detection. |\n| Cloudflare Managed Ruleset | ...c12cf9c8 | N/A | Anomaly:Header:User-Agent - Fake Bing or MSN Bot | Enabled | Disabled | We are changing the action for this rule from BLOCK to Disabled |","published_at":"2026-07-01T18:42:49+00:00","relation":"advisory","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"}