CVE-2026-5538
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceServer-Side Request Forgery (SSRF) vulnerability in the service_url function of the JudgeServer component within the judge_server_heartbeat endpoint of QingdaoU OnlineJudge up to v1.6.1. An attacker can manipulate the service_url parameter to make the server perform arbitrary HTTP requests to internal or external resources.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Locate the judge_server_heartbeat endpointSearch your codebase for 'judge_server_heartbeat' or 'service_url' in the source code, routing configuration, or API definitionsAffected if This endpoint exists in your deployment
-
Identify service_url parameter handlingExamine the function handling the service_url parameter in the judge_server_heartbeat endpoint; look for URL construction or network request logicAffected if The endpoint processes a service_url parameter without strict validation
-
Check URL validation logicReview the code for URL validation, allowlist enforcement, or sanitization applied to the service_url parameter before making outbound requestsAffected if No strict URL validation or allowlisting is implemented on the service_url parameter
-
Verify endpoint accessibilityDetermine if the judge_server_heartbeat endpoint is exposed to unauthenticated or low-privilege users via your web server, API gateway, or routing configurationAffected if The endpoint is accessible to remote attackers without proper access controls
-
Assess outbound network capabilityCheck if the server running this endpoint has outbound network access and can reach arbitrary hostsAffected if The server can initiate outbound network connections based on attacker-supplied URLs
You are affected if the judge_server_heartbeat endpoint is exposed and processes a service_url parameter without strict URL validation and access controls, allowing arbitrary outbound requests.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement strict input validation and whitelisting for the service_url parameter; restrict network access to prevent requests to internal/infrastructure addresses; apply network segmentation to limit exposure.
- Consultation3.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-5538 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-5538 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data