Vulnerability-Lookup

GHSA-588Q-HR78-M65W

Vulnerability from github – Published: 2026-09-09 06:31 – Updated: 2026-09-09 06:31

Details

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fallback' Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. 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. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \x3cscript\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core's shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink.

Severity

6.4 (Medium)


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

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-77186"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-09T04:19:55Z",
    "severity": "MODERATE"
  },
  "details": "The My Calendar \u2013 Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via \u0027fallback\u0027 Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. 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. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \\x3cscript\\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core\u0027s shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink.",
  "id": "GHSA-588q-hr78-m65w",
  "modified": "2026-09-09T06:31:37Z",
  "published": "2026-09-09T06:31:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77186"
    },
    {
      "type": "WEB",
      "url": "https://github.com/joedolson/my-calendar/commit/89bbf7314fac84cdb89e520e8b7b6d69eee8dd3c"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-shortcodes.php#L114"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-widgets.php#L272"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar.php#L556"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/62c8fb1f-6cba-43cc-8aca-70812c29a63d?source=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-77186 (GCVE-0-2026-77186)

Vulnerability from cvelistv5 – Published: 2026-09-09 03:28 – Updated: 2026-09-09 13:12

Title

My Calendar <= 3.8.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'fallback' Shortcode Attribute

Summary

Severity

6.4 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-09 13:12 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

Wordfence mitre root

References

5 references

URL	Tags
https://www.wordfence.com/threat-intel/vulnerabil…
https://plugins.trac.wordpress.org/browser/my-cal…
https://plugins.trac.wordpress.org/browser/my-cal…
https://plugins.trac.wordpress.org/browser/my-cal…
https://github.com/joedolson/my-calendar/commit/8…

Impacted products

1 product

Vendor	Product	Version
joedolson	My Calendar – Accessible Event Manager	Affected: 0 , ≤ 3.8.3 (semver)

Credits

Wordfence PRISM

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77186",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-09T13:12:19.352858Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-09T13:12:36.335Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "My Calendar \u2013 Accessible Event Manager",
          "vendor": "joedolson",
          "versions": [
            {
              "lessThanOrEqual": "3.8.3",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Wordfence PRISM"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The My Calendar \u2013 Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via \u0027fallback\u0027 Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. 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. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \\x3cscript\\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core\u0027s shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 6.4,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-09T03:28:47.091Z",
        "orgId": "b15e7b5b-3da4-40ae-a43c-f7aa60e62599",
        "shortName": "Wordfence"
      },
      "references": [
        {
          "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/62c8fb1f-6cba-43cc-8aca-70812c29a63d?source=cve"
        },
        {
          "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-widgets.php#L272"
        },
        {
          "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-shortcodes.php#L114"
        },
        {
          "url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar.php#L556"
        },
        {
          "url": "https://github.com/joedolson/my-calendar/commit/89bbf7314fac84cdb89e520e8b7b6d69eee8dd3c"
        }
      ],
      "timeline": [
        {
          "lang": "en",
          "time": "2026-08-20T16:51:45.000Z",
          "value": "Vendor Notified"
        },
        {
          "lang": "en",
          "time": "2026-09-08T14:30:06.000Z",
          "value": "Disclosed"
        }
      ],
      "title": "My Calendar \u003c= 3.8.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via \u0027fallback\u0027 Shortcode Attribute"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "b15e7b5b-3da4-40ae-a43c-f7aa60e62599",
    "assignerShortName": "Wordfence",
    "cveId": "CVE-2026-77186",
    "datePublished": "2026-09-09T03:28:47.091Z",
    "dateReserved": "2026-08-20T16:36:39.274Z",
    "dateUpdated": "2026-09-09T13:12:36.335Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.