# CVE-2026-116883: Semantic MediaWiki 3.1.0 before 7.3.1 Stored XSS via Schema Descriptions

Status: published. Published: 2026-10-27. Updated: 2026-11-04.

Semantic MediaWiki from 3.1.0 before 7.3.1 contains a stored cross-site scripting vulnerability that allows authenticated schema editors to inject HTML through schema descriptions. Attackers with the smw-schemaedit permission can save HTML that is passed unescaped to Html::rawElement() in HtmlBuilder, altering pages and targeting users who view the schema.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- SemanticMediaWiki / SemanticMediaWiki: ≥ 3.1.0; < 7.3.1 (affected, semver); 7.3.1 (unaffected, semver). Source: CNA: VulnCheck

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:semantic-mediawiki:semantic_mediawiki:*:*:*:*:*:mediawiki:*:*",
            "versionEndExcluding": "7.3.1",
            "versionStartIncluding": "3.1.0",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 4.0: 4.8 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 4.8 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/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; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.15% as of 2026-11-04; percentile 4.02%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

- exploit: https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (ADP: CISA-ADP)
- exploit: https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (disclosure@vulncheck.com)
- exploit: https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## References

- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/semantic-mediawiki-3.1.0-before-7.3.1-stored-xss-via-schema-descriptions (CNA: VulnCheck; third-party-advisory)

- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (ADP: CISA-ADP; exploit)

- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (disclosure@vulncheck.com; Exploit, Mitigation, Vendor Advisory)

- https://www.vulncheck.com/advisories/semantic-mediawiki-3.1.0-before-7.3.1-stored-xss-via-schema-descriptions (disclosure@vulncheck.com; Third Party Advisory)

- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-2xr9-cr6h-wr6m (134c704f-9b21-4f2e-91b3-4a467353bcc0; Exploit, Mitigation, Vendor Advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-116883; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116883; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116883; retrieved 2026-11-04; source updated Not reported

Revision: e8e1e47306d86fec3a3508c7bc6374a9209b5165f394615e271df53a145070a9

Canonical: https://y2.dev/cve/CVE-2026-116883

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.