CVE intelligence and bounded remediation

CVE-2023-3550 — Mediawiki v1.40.0 does not validate namespaces used in XML files

Critical CVSS 9

Mediawiki v1.40.0 does not validate namespaces used in XML files. Therefore, if the instance administrator allows XML file uploads, a remote attacker with a low-privileged user account can use this exploit to become an administrator by sending a malicious link to the instance administrator.

Severity
Critical
CVSS
9 (3.1)
Published
2023-09-25
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • mediawiki / mediawiki / 1.40.0
  • debian / debian_linux / 10.0
  • debian / debian_linux / 11.0

Matched remediation archetype

Cross-site scripting and unsafe browser output

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Check exposure

  • Trace reflected, stored, and DOM-derived untrusted values into HTML, attributes, URLs, styles, scripts, and client-side template sinks.
  • Identify affected origins, authenticated user roles, sensitive browser capabilities, and where content is shared across tenants.
  • Review framework escaping, rich-text sanitization, legacy templates, and client-side rendering paths.

Remediate safely

  • Use context-aware framework output encoding and safe DOM APIs; keep untrusted data out of executable contexts.
  • Sanitize intentionally supported markup with a maintained allowlist policy and validate URLs and attributes separately.
  • Update affected rendering components and add tests for every output context using inert sentinel markup.

Authoritative sources

Complete CVE record and remediation plan

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