---
id: CVE-2026-70667
title: Lemur manages TLS certificate creation
summary: >-
  Lemur manages TLS certificate creation. Prior to 1.9.3,
  _validate_revocation_url in lemur/certificates/verify.py checked the original
  CRL or OCSP URL but the later request could reach a different destination. The
  CRL requests.get call fo…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L'
cwe:
  - CWE-367
  - CWE-918
vendor: lemur
product: lemur
affected:
  - lemur < 1.9.3
patched:
  - lemur 1.9.3
published: '2026-08-18'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T21:02:26.047'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-70667'
references:
  - url: >-
      https://github.com/Netflix/lemur/commit/ed504a830f38a83825b1570302e9f38d6553938a
    label: security-advisories@github.com
  - url: 'https://github.com/Netflix/lemur/releases/tag/v1.9.3'
    label: security-advisories@github.com
  - url: 'https://github.com/Netflix/lemur/security/advisories/GHSA-f3qq-49m6-rw8f'
    label: security-advisories@github.com
  - url: 'https://github.com/Netflix/lemur/security/advisories/GHSA-54vg-pfh7-jq95'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/advisories/GHSA-f3qq-49m6-rw8f'
tags:
  - nvd
  - ghsa
  - pip
epss: 0.00179
epssPercentile: 0.06621
aliases:
  - GHSA-f3qq-49m6-rw8f
ecosystem: pip
ingestedAt: '2026-08-18T21:22:59.795Z'
---

## Overview

Lemur manages TLS certificate creation. Prior to 1.9.3, _validate_revocation_url in lemur/certificates/verify.py checked the original CRL or OCSP URL but the later request could reach a different destination. The CRL requests.get call followed HTTP redirects without validating each Location target, so a public attacker-controlled URL could redirect to loopback, RFC1918, link-local, or instance-metadata addresses. Validation and connection also performed separate DNS resolutions, creating a time-of-check time-of-use window for DNS rebinding on both CRL and OCSP paths. An operator uploading a certificate through POST /api/1/certificates/upload could therefore induce blind internal requests despite the earlier mitigation. The fix disables redirects and pins validated addresses while preserving the correct Host value. This issue is fixed in version 1.9.3.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-70667)

Affected packages:

- `lemur < 1.9.3`

Patched in:

- `lemur 1.9.3`

Source: https://github.com/advisories/GHSA-f3qq-49m6-rw8f