# CVE-2026-21728: Tempo query limit results in unbounded memory allocation

> Attackers can cause denial of service in Grafana Tempo by sending queries with large limits, leading to unbounded memory allocation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Apr 2026
- **Updated:** 9 Sep 2026
- **Also known as:** CLEANSTART-2026-DW50999, CLEANSTART-2026-IZ25531, CLEANSTART-2026-NL77468, CLEANSTART-2026-XP22570, ECHO-854a-eb69-2b5a, GHSA-p4r4-xvrq-gvmc, GO-2026-5528, MINI-27vv-29qw-7w5p, MINI-2ffq-pqq7-45cm, MINI-5qgm-jmph-7j6v, MINI-684r-fwh4-v977, MINI-6p7c-gvmv-4qw8, MINI-8jpj-8c3p-9p4x, MINI-93jq-29x4-hxw6, MINI-93pv-x94c-m252, MINI-c227-m969-wrch, MINI-f35m-wr67-cwpp, MINI-f4vx-c66r-89rg, MINI-hqwc-g687-88jx, MINI-hw3c-gjq9-gc6c, MINI-j34p-v3vw-v49h, MINI-vp4v-pxgg-f9rc, MINI-w5vp-7cxm-5qfj, MINI-wq8p-r9wc-26rc, MINI-x828-xq5p-q9f4

## What is CVE-2026-21728?

CVE-2026-21728 is a high-severity denial of service vulnerability in Grafana Enterprise Traces (GET), published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-21728?

7 open source packages ship an affected version, including github.com/grafana/tempo. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/grafana/tempo` | Go | From 1.3.0 | None |
| `github.com/grafana/tempo` | Go | From 1.3.0 | 2.8.4 |
| `github.com/grafana/tempo` | Go | From 1.3.0 | 2.8.4 |
| `github.com/grafana/tempo` | Go | From 2.10.0 | 2.10.2 |
| `github.com/grafana/tempo` | Go | From 2.10.0 | 2.10.2 |
| `github.com/grafana/tempo` | Go | From 2.9.0 | 2.9.2 |
| `github.com/grafana/tempo` | Go | From 2.9.0 | 2.9.2 |

Products: Grafana Tempo.

## How do I fix CVE-2026-21728?

Upgrade github.com/grafana/tempo to a fixed version for your release line: 2.8.4, 2.10.2 or 2.9.2.

## Is CVE-2026-21728 being exploited?

There is no known exploitation of CVE-2026-21728 in the wild and no public exploit code.

## Other vulnerabilities in Grafana Enterprise Traces (GET)

- [CVE-2026-28377](https://insights.sbomify.com/CVE-2026-28377/): S3 SSE-C Encryption Key Exposed in Plaintext via Config Endpoint (CVE-2025-41118 Pattern) (high 7.5)
- [CVE-2026-27878](https://insights.sbomify.com/CVE-2026-27878/): Tempo TraceQL query with exemplar hint could result in unbounded memory usage (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21728 and fix it if it is affected.

What it is: CVE-2026-21728 is a high-severity denial of service vulnerability in Grafana Enterprise Traces (GET), published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-21728 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/grafana/tempo (Go): affected from 1.3.0; no fix listed
- github.com/grafana/tempo (Go): affected from 1.3.0; fixed in 2.8.4
- github.com/grafana/tempo (Go): affected from 1.3.0; fixed in 2.8.4
- github.com/grafana/tempo (Go): affected from 2.10.0; fixed in 2.10.2
- github.com/grafana/tempo (Go): affected from 2.10.0; fixed in 2.10.2
- github.com/grafana/tempo (Go): affected from 2.9.0; fixed in 2.9.2
- github.com/grafana/tempo (Go): affected from 2.9.0; fixed in 2.9.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-21728/ (Markdown: https://insights.sbomify.com/CVE-2026-21728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21728
- OSV: https://osv.dev/vulnerability/CVE-2026-21728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21728/
Summaries are generated and may contain mistakes; the official description above is the record.