VulnerabilityPublished 1 Mar 2026Updated 2 Mar 2026

CVE-2026-3395: MaxSite CMS · Code Injection

Affects MaxSite CMSSource CVE Database V5

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Public exploit available · CVSS 6.9 Medium · fixed in 109.2 : patch MaxSite CMS as a priority.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 4.0% chance of exploitation in 30 days – higher than 90% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 109.2

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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: None
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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
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 1 Mar 2026
Detectable: evidence found.
nuclei template: MaxSite CMS <=109.1 - Remote Code Execution
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
MaxSiteCMS	Affected =109.0 =109.1	Fixed in–
GitHubmaxsite/cms`pkg:github/maxsite/cms`Other threats	Affected =109.0 =109.1	Fixed in–

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AI-suggested

Immediate upgrade to MaxSite CMS version 109.2 is the primary mitigation to eliminate the vulnerable code path. Until upgrade is possible, organizations should restrict access to the affected endpoint (application/maxsite/admin/plugins/editor_markitup/preview-ajax.php) via web application firewalls (WAFs) or network-level controls to block suspicious requests. Implement strict input validation and sanitization on any user-supplied data processed by the CMS, especially where eval or similar functions are used. Monitor web server logs for unusual or suspicious activity targeting the MarkItUp Preview AJAX Endpoint. Employ intrusion detection systems (IDS) to detect exploitation attempts. Regularly audit CMS plugins and third-party components for unsafe code practices. Educate developers and administrators about the risks of using eval with untrusted input to prevent similar vulnerabilities in the future.

Description

A flaw has been found in MaxSite CMS up to 109.1. This impacts the function eval of the file application/maxsite/admin/plugins/editor_markitup/preview-ajax.php of the component MarkItUp Preview AJAX Endpoint. Executing a manipulation can lead to code injection. It is possible to launch the attack remotely. The exploit has been published and may be used. Upgrading to version 109.2 will fix this issue. This patch is called 08937a3c5d672a242d68f53e9fccf8a748820ef3. You should upgrade the affected component. The code maintainer was informed beforehand about the issues. He reacted very fast and highly professional.

Impact

The vulnerability allows remote attackers to execute arbitrary code on affected MaxSite CMS installations, potentially leading to full system compromise. This can result in unauthorized data access or modification, website defacement, deployment of malware, or use of the compromised server as a pivot point for further attacks. The lack of authentication and user interaction requirements makes exploitation straightforward for attackers scanning for vulnerable sites. Organizations relying on MaxSite CMS for web presence or internal portals face risks of service disruption, data breaches, and reputational damage. The published exploit code increases the urgency of patching to prevent opportunistic attacks. Although the CVSS score is medium (6.9), the real-world impact could escalate if attackers combine this vulnerability with other weaknesses or target high-value systems.

Summary

CVE-2026-3395 is a remote code injection vulnerability identified in MaxSite CMS, affecting versions 109.0 and 109.1. The vulnerability exists in the MarkItUp Preview AJAX Endpoint, specifically in the file application/maxsite/admin/plugins/editor_markitup/preview-ajax.php, where the PHP eval function is improperly used. This unsafe use of eval allows an attacker to inject and execute arbitrary PHP code remotely without requiring authentication or user interaction. The vulnerability is exploitable over the network (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The impact affects confidentiality, integrity, and availability at a low level, as indicated by the CVSS vector. Although no known exploits in the wild have been reported yet, proof-of-concept exploits have been published, increasing the likelihood of active exploitation. The MaxSite CMS maintainer responded promptly and released version 109.2 to fix the issue by removing or securing the vulnerable eval usage. This vulnerability highlights the risks of using eval with untrusted input in web applications, especially in CMS platforms that are publicly accessible and widely used for content management.

References

Community reviews

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CVE-2026-3395: MaxSite CMS · Code Injection

Exploitation evidence

What to do

Affected software

Description

Impact

Summary

Nuclei detection templates

Proofs of concept on GitHub

References

Community reviews

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Mar 2026, 01:23 UTC

Public exploits and detectiona Nuclei detection template, GitHub proofs of concept

Technical details

References

Community reviews

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