CVE-2026-111658 — SiteServer SSCMS through 7.4.0 Cross-Site Authorization Bypass via Channels API
SiteServer SSCMS through 7.4.0 contains an authorization bypass vulnerability in ChannelsController that allows site-scoped administrators to access other sites' channels by supplying foreign channel IDs. Attackers with Channels permission on one site can read and overwrite another site's channel names, file paths, templates, link URLs, and custom fields, breaking multi-site isolation.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
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.
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 (Siteserver SSCMS).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Siteserver | SSCMS | ≤ 7.4.0 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
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 |
|---|---|---|---|---|---|
| 5.1 | CVSS 4.0 | Medium | — | — | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 5.1 | CVSS 4.0 | Medium | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
| 3.8 | CVSS 3.1 | Low | 1.2 | 2.5 | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 3.8 | CVSS 3.1 | Low | — | — | GitHub, Inc. via GitHub Security Advisories |
| 3.8 | CVSS 3.1 | Low | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N (score shown at the top: disclosure@vulncheck.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CWE-639 · Authorization Bypass Through User-Controlled Key (IDOR)
EPSS over time FIRST
Oct 18, 2026 → Oct 19, 2026 · 2 reading(s) · max 0.27%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Audit administrative actions and access to resources outside each user’s normal pattern.
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Deferred
- Affected products added · siteserver/sscms
- Record published
- CVSS changed · 3.8
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 16, 2026 – Oct 16, 2026
- 1× Official description updated · Oct 16, 2026 – Oct 16, 2026
References
6 on the record
- github.com/siteserver/cms/blob/sscms-v7.2.1/src/SSCMS.Web/Controllers/Admin/Cms/
- nvd.nist.gov/vuln/detail/CVE-2026-111658
- www.vulncheck.com/advisories/siteserver-sscms-through-7.4.0-cross-site-authorization-by
- hackmd.io/@hieuPenguinnn/sscms-cross-site-channel-idor
- github.com/siteserver/cms/blob/sscms-v7.2.1/src/SSCMS.Web/Controllers/Admin/Cms/
- github.com/advisories/GHSA-f64v-vg62-99f4
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-82486 SiteServer SSCMS Agent Installation Workflow access control Aug 30, 2026
- High CVE-2026-7435 SSCMS v7.4.0 SQL Injection via stl:sqlContent queryString Apr 30, 2026
- Medium CVE-2026-7429 SSCMS v7.4.0 Reflected Cross-Site Scripting via STL Processing Apr 30, 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 CISA SSVC assessment.
- 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-2026-111658 is "SiteServer SSCMS through 7.4.0 Cross-Site Authorization Bypass via Channels API", rated Low. It affects SSCMS (Siteserver); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.8 describes technical severity. EPSS 0.27% 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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