# CVE-2026-78594: Improper Handling of Highly Compressed Data in APM Server Leading to Persistent Denial of Service

> An authenticated user can cause persistent denial of service in Elastic APM Server by uploading highly compressed source maps that exhaust memory.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** GHSA-5jf2-hccc-p8fm

## What is CVE-2026-78594?

CVE-2026-78594 is a medium-severity denial of service vulnerability in Elastic Apm Server, published on 2 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Improper Handling of Highly Compressed Data (CWE-409) in APM Server can lead to a persistent denial of service via Excessive Allocation (CAPEC-130). An authenticated user with write access to source map content could store specially crafted, highly compressed content that exhausts the memory available to APM Server when it is later processed, terminating the process. The condition recurs on every restart until the stored content is removed.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-78594?

It affects 1 product.


Products: Elastic Apm Server.

## How do I fix CVE-2026-78594?

No fix has been published for CVE-2026-78594 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78594 being exploited?

There is no known exploitation of CVE-2026-78594 in the wild and no public exploit code.

## Other vulnerabilities in Elastic Apm Server

- [CVE-2023-31421](https://insights.sbomify.com/CVE-2023-31421/): Beats, Elastic Agent, APM Server, and Fleet Server Improper Certificate Validation issue (medium 5.9)
- [CVE-2024-37286](https://insights.sbomify.com/CVE-2024-37286/): APM Server Insertion of Sensitive Information into Log File (medium 5.7)
- [CVE-2024-23448](https://insights.sbomify.com/CVE-2024-23448/): APM Server Insertion of Sensitive Information into Log File (medium 5.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78594 and fix it if it is affected.

What it is: CVE-2026-78594 is a medium-severity denial of service vulnerability in Elastic Apm Server, published on 2 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-78594 in the wild and no public exploit code.

Affected product: Elastic Apm 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-2026-78594/ (Markdown: https://insights.sbomify.com/CVE-2026-78594/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78594
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78594
- OSV: https://osv.dev/vulnerability/CVE-2026-78594

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78594/
Summaries are generated and may contain mistakes; the official description above is the record.