CVE-2020-27304

What it is

The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file upload form handler, and use parts of the user-controlled filename in the output path, are susceptible to directory traversal

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

3.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-10-21 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:09 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.3% in the next 30 days (EPSS).
• Severity: 9.8 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-21 16:15 UTC

Last modified

2026-06-17 03:09 UTC

Exploit probability

3.3% · EPSS, next 30 days

Weakness

CWE-23

Record status

Modified

Affected

• Civetweb Project Civetweb < 1.15
• Siemens Sinec Infrastructure Network Services < 1.0.1.1

Attack profile CVSS 3.1 · 9.8

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-27304.md and follow it. Check whether this project is affected by CVE-2020-27304. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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