Improper Input ValidationWeakness · CWE-20

CVE-2025-32077

MEDIUM · 6.9 CVSS v4.0 Published 2025-04-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper Input Validation vulnerability in The Wikimedia Foundation Mediawiki - Extension:SimpleCalendar allows Cross-Site Scripting (XSS).This issue affects Mediawiki - Extension:SimpleCalendar: from 1.39 through 1.43.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Improper input validation in the SimpleCalendar extension for MediaWiki allows attackers to inject malicious scripts via unsanitized inputs, resulting in stored Cross-Site Scripting (XSS) that executes when other users view affected calendar content.

MitigationApply input validation and output encoding/sanitization to all user-supplied data within the SimpleCalendar extension; upgrade to a patched version if available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm SimpleCalendar extension is installed
    Check your MediaWiki installation for the SimpleCalendar extension by looking in the /extensions/ directory for a SimpleCalendar folder, or by running 'composer show' to list installed packages and look for SimpleCalendar.
    Affected if The SimpleCalendar extension is present in the MediaWiki installation.
  2. Identify the installed SimpleCalendar version
    Check the version file within the SimpleCalendar extension directory (e.g., extension.json, composer.json, or Special:Version in MediaWiki admin panel). Compare this version against any patched version released after the CVE disclosure date.
    Affected if The installed version is older than the patched version and has not received input validation/sanitization fixes.
  3. Determine if user-contributed calendar content exists
    Review the database tables used by SimpleCalendar (typically tables prefixed with 'simplecal' or similar) or inspect calendar pages created through the extension to see if they contain user-submitted event titles, descriptions, or other fields.
    Affected if User-generated content is stored and displayed in calendars without sanitization.
  4. Inspect the code for input validation
    Examine the SimpleCalendar source files (especially files handling event creation/editing) for presence of input validation functions (such as htmlspecialchars, Sanitizer methods, or other encoding functions) on user-supplied fields before storage and before output rendering.
    Affected if User input fields are processed without proper sanitization or output encoding.

The environment is affected if the SimpleCalendar extension is installed, contains a version without the CVE fix, and displays user-supplied content without sanitization.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply input validation and output encoding/sanitization to all user-supplied data within the SimpleCalendar extension; upgrade to a patched version if available.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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Scan for this in your stack

Free · runs locally
dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-32077 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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