{"schemaVersion":3,"id":"CVE-2026-55166","aliases":["GHSA-v2wp-frmc-5q3v","PYSEC-2026-384"],"status":"published","duplicateOf":null,"title":null,"description":"Lemur manages TLS certificate creation. Prior to 1.9.2, authenticated users could influence an ACME authority acme_url without an effective server-side destination restriction and trigger AcmeHandler.setup_acme_client to make backend requests. An attacker could target cloud instance metadata or internal services from Lemur network context, potentially obtaining credentials available to the host. The advisory also identifies creator-equality authorization behavior that could preserve access to certificate key material after ownership or role changes, with insufficient export_private_key audit context to distinguish that access path. Together, the acme_url server-side request forgery and authorization weakness could expose cloud credentials and long-lived PKI private-key access. The fix adds ACME_DIRECTORY_HOST_ALLOWLIST validation and enriches key-export audit events with creator and current-owner context. This issue is fixed in version 1.9.2.","dates":{"published":"2026-08-18T18:51:41.495Z","modified":"2026-08-18T19:34:19.740Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":9.9,"severity":"critical","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":9.9,"severity":"critical","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Pypi","score":9.9,"severity":"critical","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L","exploitability":7.9,"impact":10,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":9.9,"severity":"critical","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00287,"percentile":0.19906,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0.011000000000000029,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00276},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00287,"percentile":0.19906}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00276,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00287,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00287,"percentile":0.19906}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-285","name":"Improper Authorization","description":"The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.","type":"weakness","status":"Draft","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/285.html"},{"id":"CWE-639","name":"Authorization Bypass Through User-Controlled Key","description":"The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/639.html"},{"id":"CWE-918","name":"Server-Side Request Forgery (SSRF)","description":"The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/918.html"}],"affected":[{"vendor":"netflix","product":"lemur","name":"lemur","label":"lemur","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 1.9.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1.9.2","eol":null,"hubHref":"/vendor/netflix/lemur"},{"vendor":"PyPI","product":"lemur","name":"lemur","label":"lemur","ecosystem":"PyPI","cpePart":null,"purl":"pkg:pypi/lemur","purlType":"pypi","versions":[{"text":"< 1.9.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1.9.2","eol":null,"hubHref":null}],"affectedCount":2,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/Netflix/lemur/security/advisories/GHSA-v2wp-frmc-5q3v","label":"github.com/Netflix/lemur/security/advisories/GHSA-v2wp-frmc-5q3v","hostname":"github.com","tags":["X Refsource CONFIRM","WEB"]},{"url":"https://github.com/Netflix/lemur/commit/872f6e282542352f2bf3f6e2bcc504ab81e1843d","label":"github.com/Netflix/lemur/commit/872f6e282542352f2bf3f6e2bcc504ab81e1843d","hostname":"github.com","tags":["X Refsource MISC"]},{"url":"https://github.com/Netflix/lemur/releases/tag/v1.9.2","label":"github.com/Netflix/lemur/releases/tag/v1.9.2","hostname":"github.com","tags":["X Refsource MISC","WEB"]},{"url":"https://github.com/Netflix/lemur","label":"github.com/Netflix/lemur","hostname":"github.com","tags":["PACKAGE"]},{"url":"https://pypi.org/project/lemur","label":"pypi.org/project/lemur","hostname":"pypi.org","tags":["PACKAGE"]},{"url":"https://github.com/advisories/GHSA-v2wp-frmc-5q3v","label":"github.com/advisories/GHSA-v2wp-frmc-5q3v","hostname":"github.com","tags":["Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55166","label":"nvd.nist.gov/vuln/detail/CVE-2026-55166","hostname":"nvd.nist.gov","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-08-18T18:51:41.495Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-08-18T19:34:19.740Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":70,"level":"high","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T15:59:28.795Z","stale":false,"partial":false}}