CVE-2026-23835
LobeHub Vulnerable to Improper Authorization in Presigned Upload
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@lobehub/chatnpmDescription
LobeHub is an open source human-and-AI-agent network. Prior to version 1.143.3, the file upload feature in Knowledge Base > File Upload does not validate the integrity of the upload request, allowing users to intercept and modify the request parameters. As a result, it is possible to create arbitrary files in abnormal or unintended paths. In addition, since lobechat.com relies on the size parameter from the request to calculate file usage, an attacker can manipulate this value to misrepresent the actual file size, such as uploading a 1 GB file while reporting it as 10 MB, or falsely declaring a 10 MB file as a 1 GB file. By manipulating the size value provided in the client upload request, it is possible to bypass the monthly upload quota enforced by the server and continuously upload files beyond the intended storage and traffic limits. This abuse can result in a discrepancy between actual resource consumption and billing calculations, causing direct financial impact to the service operator. Additionally, exhaustion of storage or related resources may lead to degraded service availability, including failed uploads, delayed content delivery, or temporary suspension of upload functionality for legitimate users. A single malicious user can also negatively affect other users or projects sharing the same subscription plan, effectively causing an indirect denial of service (DoS). Furthermore, excessive and unaccounted-for uploads can distort monitoring metrics and overload downstream systems such as backup processes, malware scanning, and media processing pipelines, ultimately undermining overall operational stability and service reliability. Version 1.143.3 contains a patch for the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @lobehub/chat | all versions | 1.143.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @lobehub/chat. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @lobehub/chat to 1.143.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23835 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-23835 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-23835. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-23835 in your dependencies?
O3 detects CVE-2026-23835 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.