Lemur: any SSO-authenticated user achieves AWS IAM compromise and permanent PKI key access via ACME acme_url SSRF and creator-equality IDOR
CVSS score
9.9
EPSS probability
%0.3
Risk score
0.0
Published
2 mo ago
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Impact on My Inventory
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Vulnerability description
DayBreach CVE AI Research
CVE-2026-55166 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
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.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-55166 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | netflix | lemur | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 9.9 | CVSS V3_1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L | CVE CNA |
| 9.9 | CVSS V31 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-55166 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-55166 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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