# CVE-2026-59303: Dynamic destination cache size is not properly bound in Spring Cloud Stream

> An attacker can cause a denial of service by exploiting an unbounded dynamic destination cache size in Spring Cloud Stream.

- **Severity:** Low 3.1 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 27 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** GHSA-6h2m-pr57-ggxv

## What is CVE-2026-59303?

CVE-2026-59303 is a low-severity denial of service vulnerability in Spring Cloud Stream, published on 27 Aug 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Dynamic destination cache size is not properly bound in Spring Cloud Stream.
Spring Cloud Stream 5.0.0 - 5.0.2
Spring Cloud Stream 4.3.0 - 4.3.3
Spring Cloud Stream 4.2.0 - 4.2.6

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-59303?

It affects 1 product.


Products: Vmware Spring Cloud Stream.

## How do I fix CVE-2026-59303?

Upgrade to a fixed version.

## Is CVE-2026-59303 being exploited?

There is no known exploitation of CVE-2026-59303 in the wild and no public exploit code.

## Other vulnerabilities in Spring Cloud Stream

- [CVE-2026-59304](https://insights.sbomify.com/CVE-2026-59304/): Improper caching of the original content type in Spring Cloud Stream Avro (low 3.1)
- [CVE-2026-59305](https://insights.sbomify.com/CVE-2026-59305/): Partition interceptor may be improperly added while sending message (low 3.1)
- [CVE-2026-59306](https://insights.sbomify.com/CVE-2026-59306/): Potential for deserialization of untrusted types in Spring Cloud Stream (low 3.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-59303 and fix it if it is affected.

What it is: CVE-2026-59303 is a low-severity denial of service vulnerability in Spring Cloud Stream, published on 27 Aug 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-59303 in the wild and no public exploit code.

Affected product: Spring Cloud Stream. 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-2026-59303/ (Markdown: https://insights.sbomify.com/CVE-2026-59303/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59303
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59303
- OSV: https://osv.dev/vulnerability/CVE-2026-59303

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-59303/
Summaries are generated and may contain mistakes; the official description above is the record.