CVE-2026-70667
Lemur: SSRF protection in certificate revocation checking bypassable via HTTP redirects and DNS rebinding (incomplete fix for CVE-2026-55162)
Description
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.
INFO
Published Date :
Aug. 18, 2026, 7:17 p.m.
Last Modified :
Oct. 22, 2026, 10:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update Lemur to version 1.9.3.
- Apply vendor-provided patches.
- Disable HTTP redirects for certificate validation.
- Pin validated addresses for certificate verification.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-70667.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-70667 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-2026-70667
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-70667 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-70667 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 22, 2026
Action Type Old Value New Value Added Translation Title: lemur de Netflix, Description: Lemur gestiona la creación de certificados TLS. Antes de la versión 1.9.3, _validate_revocation_url en lemur/certificates/verify.py verificaba la URL original de CRL u OCSP, pero la solicitud posterior podría alcanzar un destino diferente. La llamada requests.get de CRL seguía redirecciones HTTP sin validar cada objetivo de Location, por lo que una URL pública controlada por un atacante podría redirigir a direcciones de loopback, RFC1918, link-local o de metadatos de instancia. La validación y la conexión también realizaban resoluciones DNS separadas, creando una ventana de tiempo de verificación y tiempo de uso para el DNS rebinding en ambas rutas CRL y OCSP. Un operador que subía un certificado a través de POST /api/1/certificates/upload podría, por lo tanto, inducir solicitudes internas ciegas a pesar de la mitigación anterior. La solución deshabilita las redirecciones y fija direcciones validadas mientras preserva el valor correcto de Host. Este problema está solucionado en la versión 1.9.3. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 19, 2026
Action Type Old Value New Value Added Reference https://github.com/Netflix/lemur/security/advisories/GHSA-54vg-pfh7-jq95 Added SSVC {'id': 'CVE-2026-70667', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-19T15:16:23.054190Z'} -
New CVE Received by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Netflix', 'product': 'lemur', 'versions': [{'status': 'affected', 'version': '< 1.9.3'}]}] Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L Added CWE CWE-918 Added CWE CWE-367 Added Reference https://github.com/Netflix/lemur/commit/ed504a830f38a83825b1570302e9f38d6553938a Added Reference https://github.com/Netflix/lemur/releases/tag/v1.9.3 Added Reference https://github.com/Netflix/lemur/security/advisories/GHSA-f3qq-49m6-rw8f