Low Cross-site scripting

CVE-2026-33386 — XSS in QuickCMS

QuickCMS is vulnerable to Cross-Site Scripting (XSS) through its insecure HTTP-based plugin‑fetching mechanism. A malicious attacker can perform a Man‑in‑the‑Middle (MITM) attack by impersonating the opensolution.org server and serving arbitrary HTML or JavaScript at the plugin list endpoint. When a user accesses the plugin page, the malicious content is automatically fetched, rendered, and executed. This issue was fixed in a patch to version 6.8 published on 15.05.2026, deployments without this patch are still vulnerable.

Published May 29, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: CERT-PL

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.28%

ahead of 19% of scored CVEs · Oct 14, 2026

Affects

Opensolution

Quick.cms

CVSS base

2.3

Low · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Opensolution Quick.cms).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Opensolution	Quick.cms	≤ 6.8	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Adjacent

Attack complexity

Low

Attack requirements

Present

Privileges required

None

User interaction

None

Scope

Confidentiality (vulnerable system)

None

Integrity (vulnerable system)

None

Availability (vulnerable system)

None

Confidentiality (subsequent)

Low

Integrity (subsequent)

Low

Availability (subsequent)

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
2.3	CVSS 4.0	Low	—	—	cvd@cert.pl via NIST National Vulnerability Database
2.3	CVSS 4.0	Low	—	—	CERT-PL via CVE Program (cve.org) e CISA ADP

CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/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

(score shown at the top: cvd@cert.pl)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-79 · Cross-site Scripting (XSS)

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.28%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Monitor CSP violation reports and script payloads in reflected parameters.

web/proxy/WAF logsapplication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · opensolution/quickcms
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 2.3
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Deferred
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 29, 2026 · CERT-PL

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

2 on the record

opensolution.org/home.html
product, NIST National Vulnerability Database
cert.pl/posts/2026/05/CVE-2026-33384/
third-party-advisory, NIST National Vulnerability Database

Elsewhere on this site

Opensolution
every CVE for this vendor

Cross-site scripting
same class

CWE-79
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-33385 Blind SQL Injection in Quick.CMS Jul 29, 2026
Medium CVE-2026-63303 Path Traversal in Quick.CMS Jul 28, 2026
Medium CVE-2026-63302 Local File Inclusion in Quick.CMS Jul 28, 2026
High CVE-2026-11860 Insecure Deserialisation via Plaintext HTTP leading to Remote Code Execution in Quick.CMS Jun 15, 2026
Medium CVE-2026-33384 Session Fixation in QuickCMS May 29, 2026
Medium CVE-2021-47981 Quick.CMS 6.7 Cross-Site Scripting via CSRF to Sliders Form May 16, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-33386 is "XSS in QuickCMS", rated Low. It affects Quick.cms (Opensolution); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 2.3 describes technical severity. EPSS 0.28% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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