VulnerabilityPublished 18 Jan 2026Updated 23 Feb 2026

CVE-2026-1126: lwj flow · Unrestricted Upload

Affects lwj flowSource CVE Database V5

Public exploit available · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 4.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
lwjflow	Affected =a3d2fe8133db9d3b50fda4f66f68634640344641	Fixed in–

AI-suggested

To mitigate CVE-2026-1126, organizations should immediately implement strict input validation and sanitization on all file uploads within lwj flow, especially focusing on the uploadFile function in the SVG File Handler component. Employ allowlisting of permitted file types and enforce file size limits. Implement server-side checks to verify file contents and reject suspicious or executable files. Use sandboxing or isolated environments to process uploaded files to limit potential damage. Monitor logs and network traffic for unusual upload activity or access patterns. If possible, restrict access to the upload endpoint via network segmentation or firewall rules to trusted users or IP ranges. Until an official patch is released, consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block exploit attempts targeting this vulnerability. Engage with the vendor or community to track patch releases and apply updates promptly once available. Conduct security awareness training for administrators to recognize signs of exploitation.

Description

A security vulnerability has been detected in lwj flow up to a3d2fe8133db9d3b50fda4f66f68634640344641. This affects the function uploadFile of the file \flow-master\flow-front-rest\src\main\java\com\dragon\flow\web\resource\flow\FormResource.java of the component SVG File Handler. The manipulation of the argument File leads to unrestricted upload. The attack is possible to be carried out remotely. The exploit has been disclosed publicly and may be used. This product adopts a rolling release strategy to maintain continuous delivery. Therefore, version details for affected or updated releases cannot be specified. The project was informed of the problem early through an issue report but has not responded yet.

Impact

The unrestricted file upload vulnerability poses a significant risk to organizations using lwj flow, as it can lead to unauthorized code execution, data exfiltration, or service disruption. Attackers could upload malicious files such as web shells or scripts that enable remote control over affected servers, compromising confidentiality, integrity, and availability. This could result in data breaches, lateral movement within networks, or deployment of ransomware. Since the vulnerability requires no authentication and no user interaction, it can be exploited by remote attackers with relative ease, increasing the attack surface. Organizations relying on lwj flow for critical workflows or document processing may face operational disruptions and reputational damage if exploited. The lack of vendor response and patch availability further exacerbates the risk, leaving systems exposed. The impact is particularly severe in environments where uploaded files are executed or processed without additional validation or sandboxing.

Summary

CVE-2026-1126 is a security vulnerability identified in the lwj flow product, specifically in the uploadFile function within the SVG File Handler component located in the FormResource.java file. The vulnerability stems from insufficient validation and sanitization of the file argument passed to the uploadFile function, allowing an attacker to upload arbitrary files without restrictions. This unrestricted upload capability can be exploited remotely without requiring authentication or user interaction, increasing the risk of unauthorized file placement on the server. The vulnerability affects the codebase up to commit a3d2fe8133db9d3b50fda4f66f68634640344641. Due to the product's rolling release model, no fixed version numbers are available, and the vendor has not yet issued a patch or official response. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), no user interaction (UI:N), and partial impacts on confidentiality, integrity, and availability (VC:L, VI:L, VA:L). Public disclosure of the exploit code has occurred, but no active exploitation in the wild has been confirmed. The vulnerability could be leveraged to upload malicious payloads such as web shells, ransomware, or other malware, potentially leading to system compromise, data breaches, or service disruption.

References

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