CVE-2026-21729 Loki detected_fields query limits results in unbounded memory allocation
Attackers can cause service unavailability in Grafana Loki by sending queries with large limits that trigger unbounded memory allocations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-21729?
CVE-2026-21729 is a high-severity denial of service vulnerability in Grafana Loki, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Loki queries with large limits can cause large memory allocations which can impact the availability of the service, depending on its deployment strategy.
Weakness: CWE-770
Which versions are affected by CVE-2026-21729?
How do I fix CVE-2026-21729?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-21729 being exploited?
There is no known exploitation of CVE-2026-21729 in the wild and no public exploit code.
Sources
Also known as GHSA-65p5-8cm9-qcxx, MINI-24x5-3xmm-qxhh, MINI-5v43-gwj7-p3hv, MINI-8qgg-j26m-93qx, MINI-jc2w-v5w6-pjvp.