VulnerabilityPublished 21 Aug 2025

CVE-2025-55383: Moss · Unrestricted File Upload

Source CVE Database V5

Not known to be exploited · CVSS 8.6 High · fixed in 0.15 : patch affected systems soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

8.6High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.15

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: Low
Availability: Low

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
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 on the impacted component.
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 impacted component 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 impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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), 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

AI-suggested

Immediate upgrade: Organizations should upgrade Moss to version 0.15 or later where this vulnerability is fixed. If an upgrade is not immediately possible, apply any available patches or vendor-provided workarounds.
Restrict file upload locations: Configure the upload function to restrict file uploads to specific directories with limited permissions, preventing arbitrary file placement.
Enforce file type validation: Implement strict server-side validation to allow only safe file types and reject all others, preventing dangerous file extensions from being uploaded.
Use sandboxing: Store uploaded files in isolated environments or sandboxed directories that do not have execution permissions to mitigate the risk of remote code execution.
Monitor and log uploads: Enable detailed logging and monitoring of file upload activities to detect suspicious behavior promptly.
Implement web application firewalls (WAF): Deploy WAF rules to detect and block malicious file upload attempts targeting this vulnerability.
Conduct regular security assessments: Perform penetration testing and code reviews focusing on file upload mechanisms to identify and remediate similar issues.
Educate developers and administrators: Raise awareness about secure file upload practices and the risks of unrestricted uploads to prevent recurrence.

Description

Moss before v0.15 has a file upload vulnerability. The "upload" function configuration allows attackers to upload files of any extension to any location on the target server.

Impact

For European organizations, this vulnerability poses a significant risk, especially for those using Moss in web applications or services that handle file uploads. The ability to upload arbitrary files to any location on the server can lead to unauthorized data access, data breaches, and potential system compromise. Confidential data stored on affected servers could be exposed or manipulated, violating GDPR and other data protection regulations, leading to legal and financial repercussions. Additionally, if attackers upload and execute malicious scripts or web shells, they could gain persistent access, pivot within networks, and disrupt business operations. Sectors such as finance, healthcare, government, and critical infrastructure in Europe, which often rely on secure file handling, are particularly vulnerable. The lack of authentication requirement and ease of exploitation increase the likelihood of automated attacks targeting vulnerable Moss instances. Organizations may face reputational damage and operational downtime if exploited. The absence of known exploits in the wild currently provides a window for proactive defense, but the high CVSS score indicates that exploitation could have severe consequences.

CWE-434Unrestricted Upload of File with Dangerous Type (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #12OWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
Architecture and Design
Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Architecture and Design
Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Web Service Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
File Upload (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V12.5.2 (opens in a new tab)
V13.1.5 (opens in a new tab)
V12.2.1 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/deep-project/moss/issues/16 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 21 Aug 2025, 15:18 UTC

WeaknessesCWE-434

Technical details

References

Community reviews

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