VulnerabilityPublished 31 Mar 2026

CVE-2026-5203: CMS Made Simple · Path Traversal

Affects CMS Made SimpleSource CVE Database V5

Compare

Public exploit available · CVSS 5.1 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

5.1Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/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: High
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: High: The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable system allowing full access to the vulnerable system’s settings and files.
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 31 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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
CMS Made Simple	Affected 2.2.0 – 2.2.22 23 affected builds	Fixed in–
Packagistcms/cms-made-simple`pkg:composer/cms/cms-made-simple`Other threats	Affected 2.2.0 – 2.2.22 23 affected builds	Fixed in–

CPE configurations (1)

cpe:2.3:a:cms_made_simple:cms_made_simple:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade CMS Made Simple to the latest version once the patch addressing CVE-2026-5203 is released, as this is the definitive fix.
Until patching is possible, restrict access to the UserGuide Module and its XML import functionality to trusted administrators only, minimizing exposure.
Implement strict input validation and sanitization on file path parameters within custom modules or extensions to prevent path traversal.
Employ web application firewalls (WAFs) with rules designed to detect and block path traversal attempts targeting CMS Made Simple endpoints.
Conduct regular security audits and file integrity monitoring to detect unauthorized file changes or access.
Limit the privileges of CMS users to the minimum necessary, reducing the risk that a compromised account can exploit this vulnerability.
Monitor public vulnerability disclosures and threat intelligence feeds for any signs of active exploitation to respond promptly.

Description

A vulnerability was found in CMS Made Simple up to 2.2.22. This impacts the function _copyFilesToFolder in the library modules/UserGuide/lib/class.UserGuideImporterExporter.php of the component UserGuide Module XML Import. The manipulation results in path traversal. It is possible to launch the attack remotely. The exploit has been made public and could be used. This issue has been reported early to the project. They confirmed, that "this has already been discovered and fixed for the next release."

Impact

The primary impact of CVE-2026-5203 is unauthorized file system access via path traversal, which can lead to exposure or modification of sensitive files on the web server hosting CMS Made Simple. Organizations using vulnerable CMS versions risk data leakage, including configuration files, credentials, or proprietary content. Attackers with high privileges could leverage this vulnerability to escalate their access or implant malicious files, potentially leading to website defacement, data theft, or further compromise of backend systems. Although the vulnerability requires high privileges, the fact that it can be exploited remotely increases the attack surface. This could be particularly damaging for organizations relying on CMS Made Simple for public-facing websites, intranets, or portals containing sensitive information. The medium severity rating reflects the balance between the required privileges and the potential impact. Failure to patch could result in targeted attacks against organizations with valuable data or critical web infrastructure.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

CPE configurations (1)

Description

AI analysisMachine-generated, updated 31 Mar 2026, 16:09 UTC

Public exploits and detectionGitHub proofs of concept

Technical details

References

Community reviews

Related threats