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CVE Record

CVE-2026-0556: XO Event Calendar <= 3.2.10 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'xo_event_field' shortcode

The XO Event Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'xo_event_field' shortcode in all versions up to, and including, 3.2.10 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

MediumCVSS 6.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-0556 affects the XO Event Calendar WordPress plugin through version 3.2.10. A logged-in user with Contributor or higher permissions could store script content through a calendar shortcode. That script may run when others view the affected page, creating risk to site administrators and visitors.

Executive priority

Treat as a medium-priority WordPress content integrity issue. Prioritize multi-author sites, public publishing workflows, and sites where Contributor accounts are numerous or weakly controlled. No active exploitation is cited in the provided sources.

Technical view

The issue is authenticated stored cross-site scripting in the plugin's 'xo_event_field' shortcode. Sources attribute it to insufficient sanitization and output escaping of user-supplied shortcode attributes. CVSS is 6.4, vector AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N, mapped to CWE-79.

Likely exposure

Exposure is limited to WordPress sites running XO Event Calendar versions up to and including 3.2.10, where untrusted users have Contributor-level or higher access. Public sources provided do not identify a patched version.

Exploitation context

The source bundle does not show CISA KEV listing or cite active exploitation. Exploitation requires authenticated WordPress access at Contributor level or above, reducing broad internet exposure but increasing concern for multi-author sites or compromised user accounts.

Researcher notes

The provided WordPress Trac references point to plugin code around the shortcode handling in version 3.2.10. The evidence supports stored XSS via shortcode attributes, but the bundle does not include a vendor changelog, patch commit, or fixed-version statement.

Mitigation direction

  • Inventory WordPress sites for XO Event Calendar and record plugin versions.
  • Restrict Contributor and higher roles to trusted users only.
  • Review posts and pages using the 'xo_event_field' shortcode.
  • Disable the plugin if it is not business-critical.
  • Check vendor or Wordfence guidance for a fixed version before updating.

Validation and detection

  • Confirm whether XO Event Calendar is installed on each WordPress site.
  • Flag installed versions up to and including 3.2.10.
  • Review user accounts with Contributor, Author, Editor, or Administrator roles.
  • Inspect contributor-created content using XO Event Calendar shortcodes.
  • Monitor WordPress admin activity for suspicious content changes.
Prepared
Confidence
medium
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.

cwe · medium confidence lookup

CWE-79: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-0556 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.4 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

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.

1CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.4CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N3.12.7Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

6.4Medium
CVSS 3.1 vector shape for CVE-2026-0556Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ishitakaXO Event Calendar0unaffected
Weakness

CWE details

CWE-79

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

CWE-79 · source CWE mapping

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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