CVE-2026-23835
[lobe-chat] Improper Authorization in Presigned Upload: User-controlled object key enables cross-namespace upload attempts and quota bypass
Executive Summary
CVE-2026-23835 is a medium severity vulnerability affecting ai-code, appsec. It is classified as CWE-73. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"Precogs AI automatically detects AI-specific vulnerability patterns in LLM-generated code, identifying prompt injection vectors, model poisoning risks, and insecure inference endpoints before they reach production."
What is this vulnerability?
CVE-2026-23835 is categorized as a critical Code Injection / RCE flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.
Summary The file upload feature in Knowledge Base \> File Upload does not validate the integrity of the upload request, allowing users to intercept a.
This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.
Risk Assessment
| Metric | Value |
|---|---|
| CVSS Base Score | 5.5 (MEDIUM) |
| Vector String | N/A |
| Published | January 30, 2026 |
| Last Modified | January 30, 2026 |
| Related CWEs | CWE-73 |
Impact on Systems
✅ Remote Code Execution: Attackers achieve arbitrary command execution within the context of the application server.
✅ Privilege Escalation: Initial code execution can be exploited to pivot and elevate privileges across the network.
✅ Persistent Backdoors: Attackers can bind reverse shells, modify source files, or inject persistent access mechanisms.
How to fix this issue?
Implement the following strategic mitigations immediately to eliminate the attack surface.
1. Remove Dynamic Evaluation Completely eliminate the use of dynamic evaluation functions (eval(), exec(), system()) on untrusted input.
2. Sandboxing If dynamic execution is an absolute business requirement, isolate the execution environment in tightly constrained, non-networked sandboxes (e.g., restricted WebAssembly or isolated containers).
3. Network Segmentation Restrict outbound traffic from the application server (egress filtering) to prevent reverse shell connections.
Vulnerability Signature
// Vulnerable Node.js Execution
const exec = require('child_process').exec;
const user_domain = req.query.domain;
// VULNERABLE: Injecting user input directly into system shell commands
exec('ping -c 4 ' + user_domain, (error, stdout, stderr) =\> \{
res.send(stdout);
\});
// EXPLOIT PAYLOAD: precogs.ai ; cat /etc/passwd