CVE-2026-21726: Vulnerability in Grafana Loki
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.
AI Analysis
Technical Summary
This vulnerability in Grafana Loki 2.3.0 involves improper validation of the namespace parameter in the Ruler API endpoint /loki/api/v1/rules/{namespace}. The previous fix for CVE-2021-36156 validated the parameter after a single URL decode, but an attacker can bypass this by double encoding the path traversal sequences. This allows unauthorized reading of files on the system. The CVSS 3.1 score is 5.3 (medium severity) with network attack vector, low attack complexity, no privileges or user interaction required, and confidentiality impact only.
Potential Impact
An attacker can read arbitrary files on the system hosting Grafana Loki by exploiting the path traversal vulnerability in the Ruler API endpoint. This compromises confidentiality but does not affect integrity or availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are currently available. Until a patch is released, consider restricting access to the Ruler API endpoint to trusted users or networks to reduce exposure.
CVE-2026-21726: Vulnerability in Grafana Loki
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.
CVSS v3.1
Score 5.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in Grafana Loki 2.3.0 involves improper validation of the namespace parameter in the Ruler API endpoint /loki/api/v1/rules/{namespace}. The previous fix for CVE-2021-36156 validated the parameter after a single URL decode, but an attacker can bypass this by double encoding the path traversal sequences. This allows unauthorized reading of files on the system. The CVSS 3.1 score is 5.3 (medium severity) with network attack vector, low attack complexity, no privileges or user interaction required, and confidentiality impact only.
Potential Impact
An attacker can read arbitrary files on the system hosting Grafana Loki by exploiting the path traversal vulnerability in the Ruler API endpoint. This compromises confidentiality but does not affect integrity or availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are currently available. Until a patch is released, consider restricting access to the Ruler API endpoint to trusted users or networks to reduce exposure.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GRAFANA
- Date Reserved
- 2026-01-05T09:26:06.215Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69dfeeb382d89c981f942271
Added to database: 04/15/2026, 20:01:55 UTC
Last enriched: 07/30/2026, 07:35:42 UTC
Last updated: 07/31/2026, 21:26:44 UTC
Views: 227
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