# CVE-2026-5538: QingdaoU OnlineJudge judge_server_heartbeat Endpoint JudgeServer.service_url server-side request forgery

> Remote attackers can exploit a server-side request forgery vulnerability in the judge_server_heartbeat endpoint of QingdaoU OnlineJudge.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **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:** 5 Apr 2026
- **Updated:** 6 Apr 2026
- **Also known as:** GHSA-fpw6-p57h-mv5q

## What is CVE-2026-5538?

CVE-2026-5538 is a medium-severity server-side request forgery vulnerability in QingdaoU OnlineJudge, published on 5 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was detected in QingdaoU OnlineJudge up to 1.6.1. Affected by this issue is the function service_url of the file JudgeServer.service_url of the component judge_server_heartbeat Endpoint. The manipulation results in server-side request forgery. It is possible to launch the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-5538?


## How do I fix CVE-2026-5538?

No fix has been published for CVE-2026-5538 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5538 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5538 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5538 and fix it if it is affected.

What it is: CVE-2026-5538 is a medium-severity server-side request forgery vulnerability in QingdaoU OnlineJudge, published on 5 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5538 exists.

Affected product: QingdaoU OnlineJudge. 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-2026-5538/ (Markdown: https://insights.sbomify.com/CVE-2026-5538/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5538
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5538
- OSV: https://osv.dev/vulnerability/CVE-2026-5538

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5538/
Summaries are generated and may contain mistakes; the official description above is the record.