CVE-2026-21726— Loki Path Traversal - CVE-2021-36156 Bypass
Quick assessment
Affected
Grafana Loki
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Grafana Loki是Grafana开源的一个日志聚合系统。 Grafana Loki存在安全漏洞，该漏洞源于对路径遍历序列的验证不足，可能导致攻击者通过双重编码读取Ruler API端点文件。
Possible ATT&CK Techniques 1 AI
T1083 · File and Directory Discovery
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I. Basic Information for CVE-2026-21726
Vulnerability Information
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Vulnerability Title
Loki Path Traversal - CVE-2021-36156 Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
The CVE-2021-36156 fix validates the namespace parameter for path traversal sequences after a single URL decode, by double encoding, an attacker can read files at the Ruler API endpoint /loki/api/v1/rules/{namespace}
Thanks to Prasanth Sundararajan for reporting this vulnerability.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Grafana Loki 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Grafana Loki是Grafana开源的一个日志聚合系统。 Grafana Loki存在安全漏洞，该漏洞源于对路径遍历序列的验证不足，可能导致攻击者通过双重编码读取Ruler API端点文件。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-21726
| # | POC Description | Source Link | Shenlong Link |
|---|
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Same Patch Batch · Grafana · 2026-04-15 · 4 CVEs total
| CVE-2025-41118 | 9.1 CRITICAL | Sensitive COS `SecretKey` exposed in plaintext via configuration API due to missing type p |
| CVE-2026-21727 | 3.3 LOW | Grafana Correlations: Cross-Tenant Data Disclosure and Permanent Deletion via Legacy org_i |
| CVE-2025-12141 | Grafana Alerting Editors can edit destination of webhooks they did not create |
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CVE-2026-15815 CVE Record
V. Comments for CVE-2026-21726
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