CVE-2026-21726: Grafana Loki · Path Traversal
Affects Grafana LokiSource CVE Database V5
Mentioned vulnerabilities
Not known to be exploited · CVSS 5.3 Medium : upgrade to 3.5.9 when convenient.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.5.9
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 15 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade Grafana Loki to 3.5.9.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| GrafanaLoki | Affected
| Fixed in
|
AI-suggested
If you cannot patch yet, restrict access to the Ruler API endpoint and monitor for suspicious requests involving double encoded path traversal sequences.
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.