# CVE-2026-16652: Temporal Server Schedule exclusion search can cause excessive CPU consumption

> Authenticated users can cause excessive CPU consumption and service denial by creating schedules with exclusion calendars that reject all candidate times.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** GHSA-pv35-7w89-v65c

## What is CVE-2026-16652?

CVE-2026-16652 is a high-severity denial of service vulnerability in Temporal Server, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Temporal Server did not bound the work performed while searching for a Schedule's next action time. An authenticated caller with namespace write permission could create or update a Schedule that combines a fine-grained cadence with an exclusion calendar that rejects every candidate time, causing the server to evaluate excluded candidates without a per-search work budget. This can consume excessive CPU in Frontend and Schedule worker components. A persisted specification can also cause its backing Schedule Workflow to repeatedly fail and retry, allowing CPU consumption to continue without additional requests until the Schedule is deleted or its backing Workflow is terminated. Repeated or parallel exploitation can deny service. The issue affects availability only; it does not expose or modify Workflow data.

Weakness: CWE-606 (Unchecked Input for Loop Condition)

## Which versions are affected by CVE-2026-16652?


## How do I fix CVE-2026-16652?

No fix has been published for CVE-2026-16652 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-16652 being exploited?

There is no known exploitation of CVE-2026-16652 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16652 and fix it if it is affected.

What it is: CVE-2026-16652 is a high-severity denial of service vulnerability in Temporal Server, published on 21 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-16652 in the wild and no public exploit code.

Affected product: Temporal Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-16652/ (Markdown: https://insights.sbomify.com/CVE-2026-16652/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16652
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16652
- OSV: https://osv.dev/vulnerability/CVE-2026-16652

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16652/
Summaries are generated and may contain mistakes; the official description above is the record.