CVE-2026-21728 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in github.com/grafana/tempo. A fix is available for github.com/grafana/tempo — see the affected versions and patch details below.
Tempo query limit results in unbounded memory allocation
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-21728.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/grafana/tempo🐹github.com/grafana/tempo🐹github.com/grafana/tempoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Tempo queries with large limits can cause large memory allocations which can impact the availability of the service, depending on its deployment strategy.
Mitigation can be done by setting max_result_limit in the search config, e.g. to 262144 (2^18). Alternatively, automatically restart the service.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/grafana/tempo | ≥ 1.3.0&&< 2.8.4 | 2.8.4go get github.com/grafana/tempo@v2.8.4 |
| 🐹Go | github.com/grafana/tempo | ≥ 2.9.0&&< 2.9.2 | 2.9.2go get github.com/grafana/tempo@v2.9.2 |
| 🐹Go | github.com/grafana/tempo | ≥ 2.10.0&&< 2.10.2 | 2.10.2go get github.com/grafana/tempo@v2.10.2 |
Affected Products
tempografanaDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/grafana/tempo, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/grafana/tempo to 2.8.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-21728 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated as having an Important security impact because remote unauthenticated actors can send queries configured with excessively large limit values, inducing unbounded memory consumption that results in a denial of service. In Red Hat OpenShift distributed tracing environments, components exposing…
| Product | Fixed in | Advisory |
|---|---|---|
| Multicluster Global Hub 1.3.4 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779212259 | RHSA-2026:22423 |
| Multicluster Global Hub 1.4.9 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779579439 | RHSA-2026:22347 |
| Multicluster Global Hub 1.5.8 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1778867753 | RHSA-2026:21769 |
| Multicluster Global Hub 1.6.6 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1780167118 | RHSA-2026:23345 |
| Multicluster Global Hub 1.7.3 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779925273 | RHSA-2026:24503 |
Frequently Asked Questions
Is CVE-2026-21728 in your dependencies?
Find it across Go, including transitive dependencies.