Vulnerability-Lookup

CVE-2026-75526 (GCVE-0-2026-75526)

Vulnerability from cvelistv5 – Published: 2026-08-20 18:11 – Updated: 2026-08-20 19:20

Title

django CMS: Stored XSS in edit-mode plugin exception rendering

Summary

django CMS is an easy-to-use and developer-friendly enterprise content management system powered by Django. From 5.0.8 until 5.0.9, ContentRenderer.render_placeholder in cms/plugin_rendering.py can pass stored, attacker-controlled values to ContentRenderer.render_exception when plugin rendering fails in edit mode. Values from get_short_description(), the exception message, the placeholder, or placeholder.source are interpolated into a cms-rendering-exception heading and later returned through mark_safe. Because the heading is not escaped, stored HTML executes in an editor’s browser, and settings.DEBUG does not prevent the custom heading from rendering. The fix uses format_html to escape the message before safe placeholder output is returned. This issue is fixed in versions 5.0.9.

Severity

4.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:L/UI:R/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 2026-08-20 19:20 UTC

CWE

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

Assigner

GitHub_M mitre root Scorecard

References

4 references

URL	Tags
https://github.com/django-cms/django-cms/security…	x_refsource_CONFIRM
https://github.com/django-cms/django-cms/pull/8711	x_refsource_MISC
https://github.com/django-cms/django-cms/commit/b…	x_refsource_MISC
https://github.com/django-cms/django-cms/releases…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
django-cms	django-cms	Affected: >= 5.0.8, < 5.0.9	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-75526

Vulnerability from fkie_nvd - Published: 2026-08-20 19:17 - Updated: 2026-09-09 21:19

Severity

4.4 (Medium) - CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/django-cms/django-cms/commit/b56a568844ff3702495945f73a31d0868285bf88
	security-advisories@github.com	https://github.com/django-cms/django-cms/pull/8711
	security-advisories@github.com	https://github.com/django-cms/django-cms/releases/tag/5.0.9
	security-advisories@github.com	https://github.com/django-cms/django-cms/security/advisories/GHSA-hvq6-2r72-p2x7

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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        {
          "product": "django-cms",
          "vendor": "django-cms",
          "versions": [
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              "status": "affected",
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            }
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    }
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GHSA-HVQ6-2R72-P2X7

Vulnerability from github – Published: 2026-08-20 18:42 – Updated: 2026-08-20 18:42

Summary

django CMS: Stored XSS in edit-mode plugin exception rendering

Details

Summary

When plugin rendering fails in edit mode, django CMS renders a cms-rendering-exception block so editors can see that a placeholder could not be rendered. Older code built that block's heading by interpolating the exception message, placeholder/source strings, and the failing plugin's short description directly into an HTML string, then returned the placeholder output as safe markup.

If an editor could store HTML in data used by a plugin's get_short_description() (or in other values interpolated into the exception message), and that plugin later raised during edit-mode rendering, the payload was parsed as HTML in the staff user's browser. This is a stored XSS condition in the CMS editing context.

Impact

The vulnerable path is only reached when placeholder rendering catches a plugin rendering exception:

try:
    placeholder_content = "".join(plugin_content)
except Exception as e:
    context["exc_info"] = sys.exc_info()
    placeholder_content = self.render_exception("rendering placeholder", context, placeholder, editable)

render_exception() constructs a message from values that can include stored content:

value - the exception message.
placeholder - the placeholder string representation.
placeholder.source - the source object string representation, such as page content.
instance.get_short_description() - plugin-provided summary text, often derived from plugin model fields.

In the vulnerable implementation, that message was embedded directly into an HTML heading. The final placeholder content was later returned through mark_safe, so Django template autoescaping did not protect the heading.

settings.DEBUG does not mitigate the issue: it only controls whether Django's traceback HTML is appended. The custom heading is rendered in edit mode regardless of DEBUG.

Patch

Escape the custom exception heading before returning it as safe placeholder markup. The current fixed code uses format_html, which escapes message before inserting it into the heading:

heading = format_html('<h2 class="cms-rendering-exception-title">{}</h2>', message)

The traceback HTML from ExceptionReporter.get_traceback_html() should remain separate from django CMS's custom heading; Django's traceback escaping does not protect additional HTML assembled by django CMS.

Workarounds

Until patched, reduce exposure by ensuring only fully trusted staff can edit plugins whose stored fields are included in get_short_description(), and fix or disable plugins that can be made to raise during edit-mode rendering. This is only a partial mitigation because the escaping bug is in the shared exception-rendering path.

References

cms/plugin_rendering.py - ContentRenderer.render_placeholder
cms/plugin_rendering.py - ContentRenderer.render_exception
Fixed code: heading = format_html('<h2 class="cms-rendering-exception-title">{}</h2>', message)
Regression tests: cms.tests.test_plugin_renderers.TestExceptionCatchers.test_exception_in_plugin_render_escapes_user_content_in_edit_mode, cms.tests.test_plugin_renderers.TestLegacyRendererExceptionCatcher.test_exception_in_plugin_render_escapes_user_content_in_edit_mode

Severity

4.4 (Medium)


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

Show details on source website

JSON

To clipboard

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        "name": "django-cms"
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          "events": [
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          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-75526"
  ],
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      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-20T18:42:36Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nWhen plugin rendering fails in edit mode, django CMS renders a `cms-rendering-exception` block so editors can see that a placeholder could not be rendered. Older code built that block\u0027s heading by interpolating the exception message, placeholder/source strings, and the failing plugin\u0027s short description directly into an HTML string, then returned the placeholder output as safe markup.\n\nIf an editor could store HTML in data used by a plugin\u0027s `get_short_description()` (or in other values interpolated into the exception message), and that plugin later raised during edit-mode rendering, the payload was parsed as HTML in the staff user\u0027s browser. This is a stored XSS condition in the CMS editing context.\n\n## Impact\n\nThe vulnerable path is only reached when placeholder rendering catches a plugin rendering exception:\n\n```python\ntry:\n    placeholder_content = \"\".join(plugin_content)\nexcept Exception as e:\n    context[\"exc_info\"] = sys.exc_info()\n    placeholder_content = self.render_exception(\"rendering placeholder\", context, placeholder, editable)\n```\n\n`render_exception()` constructs a `message` from values that can include stored content:\n\n- `value` - the exception message.\n- `placeholder` - the placeholder string representation.\n- `placeholder.source` - the source object string representation, such as page content.\n- `instance.get_short_description()` - plugin-provided summary text, often derived from plugin model fields.\n\nIn the vulnerable implementation, that message was embedded directly into an HTML heading. The final placeholder content was later returned through `mark_safe`, so Django template autoescaping did not protect the heading.\n\n`settings.DEBUG` does not mitigate the issue: it only controls whether Django\u0027s traceback HTML is appended. The custom heading is rendered in edit mode regardless of `DEBUG`.\n\n## Patch\n\nEscape the custom exception heading before returning it as safe placeholder markup. The current fixed code uses `format_html`, which escapes `message` before inserting it into the heading:\n\n```python\nheading = format_html(\u0027\u003ch2 class=\"cms-rendering-exception-title\"\u003e{}\u003c/h2\u003e\u0027, message)\n```\n\nThe traceback HTML from `ExceptionReporter.get_traceback_html()` should remain separate from django CMS\u0027s custom heading; Django\u0027s traceback escaping does not protect additional HTML assembled by django CMS.\n\n## Workarounds\n\nUntil patched, reduce exposure by ensuring only fully trusted staff can edit plugins whose stored fields are included in `get_short_description()`, and fix or disable plugins that can be made to raise during edit-mode rendering. This is only a partial mitigation because the escaping bug is in the shared exception-rendering path.\n\n## References\n\n- `cms/plugin_rendering.py` - `ContentRenderer.render_placeholder`\n- `cms/plugin_rendering.py` - `ContentRenderer.render_exception`\n- Fixed code: `heading = format_html(\u0027\u003ch2 class=\"cms-rendering-exception-title\"\u003e{}\u003c/h2\u003e\u0027, message)`\n- Regression tests:\n  `cms.tests.test_plugin_renderers.TestExceptionCatchers.test_exception_in_plugin_render_escapes_user_content_in_edit_mode`,\n  `cms.tests.test_plugin_renderers.TestLegacyRendererExceptionCatcher.test_exception_in_plugin_render_escapes_user_content_in_edit_mode`",
  "id": "GHSA-hvq6-2r72-p2x7",
  "modified": "2026-08-20T18:42:36Z",
  "published": "2026-08-20T18:42:36Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/security/advisories/GHSA-hvq6-2r72-p2x7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/pull/8711"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/commit/b56a568844ff3702495945f73a31d0868285bf88"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/django-cms/django-cms"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/releases/tag/5.0.9"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "django CMS: Stored XSS in edit-mode plugin exception rendering"
}

PYSEC-2026-3825

Vulnerability from pysec - Published: 2026-09-10 09:44 - Updated: 2026-09-10 11:02

Details

Summary

Impact

The vulnerable path is only reached when placeholder rendering catches a plugin rendering exception:

try:
    placeholder_content = "".join(plugin_content)
except Exception as e:
    context["exc_info"] = sys.exc_info()
    placeholder_content = self.render_exception("rendering placeholder", context, placeholder, editable)

render_exception() constructs a message from values that can include stored content:

value - the exception message.
placeholder - the placeholder string representation.
placeholder.source - the source object string representation, such as page content.
instance.get_short_description() - plugin-provided summary text, often derived from plugin model fields.

settings.DEBUG does not mitigate the issue: it only controls whether Django's traceback HTML is appended. The custom heading is rendered in edit mode regardless of DEBUG.

Patch

Escape the custom exception heading before returning it as safe placeholder markup. The current fixed code uses format_html, which escapes message before inserting it into the heading:

heading = format_html('<h2 class="cms-rendering-exception-title">{}</h2>', message)

Workarounds

References

cms/plugin_rendering.py - ContentRenderer.render_placeholder
cms/plugin_rendering.py - ContentRenderer.render_exception
Fixed code: heading = format_html('<h2 class="cms-rendering-exception-title">{}</h2>', message)
Regression tests: cms.tests.test_plugin_renderers.TestExceptionCatchers.test_exception_in_plugin_render_escapes_user_content_in_edit_mode, cms.tests.test_plugin_renderers.TestLegacyRendererExceptionCatcher.test_exception_in_plugin_render_escapes_user_content_in_edit_mode

Severity

4.4 (Medium)


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

Impacted products

Name	purl
django-cms	pkg:pypi/django-cms

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "django-cms",
        "purl": "pkg:pypi/django-cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.8"
            },
            {
              "fixed": "5.0.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "5.0.8"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-75526",
    "GHSA-hvq6-2r72-p2x7"
  ],
  "details": "## Summary\n\nWhen plugin rendering fails in edit mode, django CMS renders a `cms-rendering-exception` block so editors can see that a placeholder could not be rendered. Older code built that block\u0027s heading by interpolating the exception message, placeholder/source strings, and the failing plugin\u0027s short description directly into an HTML string, then returned the placeholder output as safe markup.\n\nIf an editor could store HTML in data used by a plugin\u0027s `get_short_description()` (or in other values interpolated into the exception message), and that plugin later raised during edit-mode rendering, the payload was parsed as HTML in the staff user\u0027s browser. This is a stored XSS condition in the CMS editing context.\n\n## Impact\n\nThe vulnerable path is only reached when placeholder rendering catches a plugin rendering exception:\n\n```python\ntry:\n    placeholder_content = \"\".join(plugin_content)\nexcept Exception as e:\n    context[\"exc_info\"] = sys.exc_info()\n    placeholder_content = self.render_exception(\"rendering placeholder\", context, placeholder, editable)\n```\n\n`render_exception()` constructs a `message` from values that can include stored content:\n\n- `value` - the exception message.\n- `placeholder` - the placeholder string representation.\n- `placeholder.source` - the source object string representation, such as page content.\n- `instance.get_short_description()` - plugin-provided summary text, often derived from plugin model fields.\n\nIn the vulnerable implementation, that message was embedded directly into an HTML heading. The final placeholder content was later returned through `mark_safe`, so Django template autoescaping did not protect the heading.\n\n`settings.DEBUG` does not mitigate the issue: it only controls whether Django\u0027s traceback HTML is appended. The custom heading is rendered in edit mode regardless of `DEBUG`.\n\n## Patch\n\nEscape the custom exception heading before returning it as safe placeholder markup. The current fixed code uses `format_html`, which escapes `message` before inserting it into the heading:\n\n```python\nheading = format_html(\u0027\u003ch2 class=\"cms-rendering-exception-title\"\u003e{}\u003c/h2\u003e\u0027, message)\n```\n\nThe traceback HTML from `ExceptionReporter.get_traceback_html()` should remain separate from django CMS\u0027s custom heading; Django\u0027s traceback escaping does not protect additional HTML assembled by django CMS.\n\n## Workarounds\n\nUntil patched, reduce exposure by ensuring only fully trusted staff can edit plugins whose stored fields are included in `get_short_description()`, and fix or disable plugins that can be made to raise during edit-mode rendering. This is only a partial mitigation because the escaping bug is in the shared exception-rendering path.\n\n## References\n\n- `cms/plugin_rendering.py` - `ContentRenderer.render_placeholder`\n- `cms/plugin_rendering.py` - `ContentRenderer.render_exception`\n- Fixed code: `heading = format_html(\u0027\u003ch2 class=\"cms-rendering-exception-title\"\u003e{}\u003c/h2\u003e\u0027, message)`\n- Regression tests:\n  `cms.tests.test_plugin_renderers.TestExceptionCatchers.test_exception_in_plugin_render_escapes_user_content_in_edit_mode`,\n  `cms.tests.test_plugin_renderers.TestLegacyRendererExceptionCatcher.test_exception_in_plugin_render_escapes_user_content_in_edit_mode`",
  "id": "PYSEC-2026-3825",
  "modified": "2026-09-10T11:02:03.695290Z",
  "published": "2026-09-10T09:44:52.636615Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/security/advisories/GHSA-hvq6-2r72-p2x7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/pull/8711"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/commit/b56a568844ff3702495945f73a31d0868285bf88"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/django-cms/django-cms"
    },
    {
      "type": "WEB",
      "url": "https://github.com/django-cms/django-cms/releases/tag/5.0.9"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/django-cms"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-hvq6-2r72-p2x7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75526"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "django CMS: Stored XSS in edit-mode plugin exception rendering"
}

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.

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.

Action not permitted

CVE-2026-75526 (GCVE-0-2026-75526)

FKIE_CVE-2026-75526

GHSA-HVQ6-2R72-P2X7

Summary

Impact

Patch

Workarounds

References

PYSEC-2026-3825

Summary

Impact

Patch

Workarounds

References

Tags

Sightings

Nomenclature

Related by attack behaviour