MaxSite CMS mail_send Plugin cross site scripting
A security vulnerability has been detected in MaxSite CMS up to 109.3. Affected by this issue is some unknown functionality of the component mail_send Plugin. The manipulation of the argument f_subject/f_files/f_from leads to cross site scripting. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. Upgrading to version 109.4 can resolve this issue. The identifier of the patch is 8a3946bd0a54bfb72a4d57179fcd253f2c550cd7. It is advisable to upgrade the affected component. The vendor was informed early about this issue. They classify it as a "Self-XSS". They deployed a countermeasure: "Nevertheless, we consider this a violation of secure coding standards. The lack of filtering via `htmlspecialchars()` has already been fixed in the latest patch to prevent incorrect data display."
- Published
- Apr 25, 2026
- Updated
- Jun 17, 2026
- EPSS
- 0.4% · 29th percentile
- CWE
- CWE-79
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Report tools
Action score
7
Monitor
Low priority for now.
- CVSS
- 7 / 40 · 1.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · VulDB
- 4.8
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (VulDB). Independent of NVD's CPE analysis and usually ahead of it.
MaxSite CMS
- 109.4not affected
- 109.0, 109.1, 109.2, 109.3affected
Same product
maxsite: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-7016MaxSite CMS ushki Plugin cross site scripting7Monitor
- CVE-2026-7015MaxSite CMS Guestbook Plugin cross site scripting7Monitor
- CVE-2026-7014MaxSite CMS down_count Plugin cross site scripting7Monitor
- CVE-2026-7012MaxSite CMS Redirect Plugin cross site scripting7Monitor
- CVE-2026-7011MaxSite CMS Antispam Plugin plugin_antispam cross site scripting7Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| MaxSite CMS | 109.4 · description | Vendor (CNA) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- VulDB CNA Teamcoordinator
- konchan (VulDB User)reporter
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-70110 days apartMaxSite CMS Antispam Plugin plugin_antispam cross site scripting7Monitor
- CVE-2026-70120 days apartMaxSite CMS Redirect Plugin cross site scripting7Monitor
- CVE-2026-70140 days apartMaxSite CMS down_count Plugin cross site scripting7Monitor
- CVE-2026-70150 days apartMaxSite CMS Guestbook Plugin cross site scripting7Monitor
- CVE-2026-70161 days apartMaxSite CMS ushki Plugin cross site scripting7Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- P
- Scope
- X
Weakness class (CWE)
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
nvd-secondary
Root cause
User content is inserted into the page as HTML. The browser interprets the content as code rather than data.
The bug in code
The whole CWE-79 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
commentEl.innerHTML = comment.body;Fixed
commentEl.textContent = comment.body;Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/maxsite/cms/
- github.com/maxsite/cms/commit/8a3946bd0a54bfb72a4d57179fcd253f2c550cd7
- github.com/maxsite/cms/releases/tag/v109
- github.com/wnaspy/CVE/blob/main/Report-%20Stored%20XSS-in-mail_send-plugin-maxsite-cms.pdf.pdf
- vuldb.com/submit/796738
- vuldb.com/vuln/359592
- vuldb.com/vuln/359592/cti
Vendor advisories and official records. Exploit/PoC links are deliberately left out.