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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-5538 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5538 exists.
Sources
Also known as GHSA-fpw6-p57h-mv5q.