LiveActive security incident?Get immediate response
CVE Record

CVE-2021-42656: SiteServer CMS V6.15.51 is affected by a Cross Site Scripting (XSS) vulnerability.

SiteServer CMS V6.15.51 is affected by a Cross Site Scripting (XSS) vulnerability.

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

SiteServer CMS V6.15.51 is reported to have a cross-site scripting vulnerability. The public bundle does not provide CVSS, affected component, attack vector, exploit status, or a named fix. Treat exposure as uncertain but worth checking wherever this CMS version is deployed.

Executive priority

Medium operational priority if SiteServer CMS V6.15.51 is in use, especially on internet-facing sites. Without evidence of active exploitation or a severity score, prioritize identification and vendor-guidance review before emergency response.

Technical view

CVE-2021-42656 describes XSS in SiteServer CMS V6.15.51. The record’s affected-product metadata is incomplete, listing n/a values, while references point to the SiteServer CMS repository, the v6.15.51 installer, and GitHub issue 3238. No CWE, CVSS, vulnerable parameter, authentication requirement, or patch version is supplied.

Likely exposure

Likely limited to organizations running SiteServer CMS V6.15.51. Exposure depends on where the vulnerable XSS exists, whether it is public, authenticated, or admin-only, and whether untrusted users can reach it. The source bundle does not confirm other versions.

Exploitation context

The bundle does not report active exploitation, and the CVE is not listed as KEV. Public references include a GitHub issue, but the prompt does not provide exploit details. Do not assume exploitation in the wild from these sources alone.

Researcher notes

Evidence is sparse. The record establishes an XSS claim for SiteServer CMS V6.15.51 but lacks root-cause detail, CVSS, CWE, authentication context, affected metadata, and remediation. Analysis should stay tied to vendor issue 3238 and avoid extrapolating to other versions.

Mitigation direction

  • Inventory SiteServer CMS deployments and identify any V6.15.51 instances.
  • Check the vendor repository and issue 3238 for confirmed remediation guidance.
  • Upgrade only to a vendor-confirmed fixed version when available.
  • Restrict access to CMS administrative or content-entry surfaces where feasible.
  • Apply standard XSS defenses such as output encoding and CSP as compensating controls.

Validation and detection

  • Confirm deployed SiteServer CMS version numbers against V6.15.51.
  • Review vendor issue 3238 for the affected page, field, or workflow.
  • Check whether untrusted users can access relevant CMS input surfaces.
  • Review recent CMS activity for suspicious stored or reflected HTML content.
  • Document uncertainty where component, vector, or fix evidence is missing.
Prepared
Confidence
low
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2021-42656 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.