CVE-2026-23835

LobeHub Vulnerable to Improper Authorization in Presigned Upload

Published Jan 30, 2026 CVSS 4.0 · 5.7 Medium EPSS < 1% KEV · Not listed

Description

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.

Analysis

Technical impact

The vulnerability allows an attacker to control the parameters of a file upload request and create files in arbitrary locations on the server. Because the upload size reported by the client is not validated, an attacker can falsify the file size to bypass monthly usage limits, potentially uploading far larger data than permitted. This can inflate billing figures, exhaust storage, and degrade performance, causing direct financial damage to the operator and offering an indirect denial of service to other users sharing the same subscription plan.

Affected Systems

Products from LobeHub (lobehub:lobe-chat) running any version earlier than 1.143.3 are affected. The vulnerability exists in the file upload feature of the Knowledge Base interface.

Risk and Exploitability

The CVSS score of 5.7 indicates moderate severity; the EPSS score is less than 1%, suggesting a low probability of widespread exploitation. The issue is not listed in the CISA KEV catalog. Exploitability requires that an attacker has access to the upload interface or can intercept traffic to manipulate request parameters. Successful exploitation would enable arbitrary file creation, quota circumvention, and potential service disruption.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

lobehub

lobe-chat

affected

Version	Status	Constraints
`< 1.143.3`	affected	—

No data.

Vendor	Product	Versions
Lobehub	Lobe Chat	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade to LobeHub version 1.143.3 or later, which contains a patch for the improper authorization bug.
Disable or restrict access to the Knowledge Base file upload endpoint until the patch is applied to prevent unauthorized file creation.
Enforce server‑side validation of the upload file path and size, and apply quota checks per project to ensure reported size matches actual data and prevent quota bypass.

Generated by OpenCVE AI on April 18, 2026 at 14:28 UTC.

Tracking

Advisories

Source	ID	Title
Github GHSA	GHSA-wrrr-8jcv-wjf5	LobeHub Vulnerable to Improper Authorization in Presigned Upload

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.366% probability within 30 days)

Exploitation poc

Automatable no

Technical Impact partial

References

Link	Providers
https://github.com/lobehub/lobehub/security/advisories/GHSA-wrrr-8jcv-wjf5

History

Feb 3, 2026 3:00 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Lobehub Lobehub lobe Chat
Vendors & Products		Lobehub Lobehub lobe Chat

Jan 30, 2026 9:15 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Jan 30, 2026 8:15 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		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.
Title		LobeHub Vulnerable to Improper Authorization in Presigned Upload
Weaknesses		CWE-73
References		https://github.com/lobehub/lobehub/security/advisories/GHSA-wrrr-8jcv-wjf5
Metrics		cvssV4_0 `{'score': 5.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:P'}`