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TI-2026-39854 Aliases CVE-2026-55166GHSA-v2wp-frmc-5q3v

Improper authorization in Netflix lemur

Priority HIGH 76CWE-285Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-285.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00287 21st percentileScored 2026-11-07
Fix Fixed lemur (Netflix): 1.9.2lemur (PyPI): 1.9.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Netflixlemurbefore 1.9.21.9.2Patch availableCNA
—lemur (PyPI)before 1.9.21.9.2Patch availableGHSA-v2wp-frmc-5q3v
  • lemur VendorNetflix Affected before 1.9.2 Fixed in 1.9.2 Patch available CNA
  • lemur (PyPI) Vendor— Affected before 1.9.2 Fixed in 1.9.2 Patch available GHSA-v2wp-frmc-5q3v

Remediation

  • Fix · CNA lemur (Netflix) Fixed in 1.9.2
  • Fix · GHSA-v2wp-frmc-5q3v lemur (PyPI) Fixed in 1.9.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55166
  2. 2026-10-03 Alias added: GHSA-v2wp-frmc-5q3v

References

Other 4

  • TI-2024-04374 Path Traversal vulnerability via File Uploads in Genie CVSS 3.1CRITICAL 9.9
  • TI-2023-21044 Dispatch writes JWT tokens in error message CVSS 3.1CRITICAL 9.1
  • TI-2026-32272 Lemur: LDAP Filter Injection enables post-authentication privilege escalation CVSS 3.1HIGH 8.1
  • TI-2026-49966 Lemur: Unchecked `replaces[]` lets any user silence notifications and hijack auto-rotation for arbitrary certificates CVSS 3.1HIGH 8.1
  • TI-2026-49965 Missing authorization in Netflix lemur CVSS 3.1HIGH 7.7
  • TI-2026-49964 Server-side request forgery in Netflix lemur CVSS 3.1HIGH 7.7
See all 33 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences