CVE-2026-23835 | LobeHub Vulnerable to Improper Authorization in Presigned Upload

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.

Published: 2026-01-30 Last update: 2026-04-15 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-23835 is rated Low Risk (31.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.33%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23835

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.01% 0.33% +0.32%
2 2026-01-31 0.01%

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23835

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 4.0 MEDIUM
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:P)
Proof-of-concept: public PoC exists; no reported exploitation and no known simplification tools.
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
[email protected]

Weakness enumeration for CVE-2026-23835

GitHub Security Advisory for CVE-2026-23835

GHSA-wrrr-8jcv-wjf5 · Severity: medium · Ecosystem: npm — LobeHub Vulnerable to Improper Authorization in Presigned Upload

Affected software / configurations for CVE-2026-23835

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-23835

cvelogic Threat Intelligence