Vulnerability-Lookup

CVE-2026-55248 (GCVE-0-2026-55248)

Vulnerability from cvelistv5 – Published: 2026-08-28 18:40 – Updated: 2026-08-28 20:35

Title

plone.app.portlets: Denial of service via RSS feed portlet

Summary

plone.app.portlets provides portlets and a Plone-specific user interface for plone.portlets. Prior to 5.0.8, 6.0.4, and 7.0.2, a member who can add an RSS portlet can set its feed URL to a very large response, causing src/plone/app/portlets/portlets/rss.py to download and retain excessive data in memory and deny service. The same RSS URL handling accepts internal hosts, IP addresses, single-word domains, and explicit ports, allowing server-side requests that can probe internal network services and open ports. A malicious feed item can also supply a JavaScript URL that is retained as the item link and can execute script when used by a victim. The affected logic includes _rss_feed_url_validator, _normal_url_validator, RSSFeed._retrieveFeed, RSSFeed._buildItemDict, and the FEED_DATA in-memory cache. This issue is fixed in versions 5.0.8, 6.0.4, and 7.0.2.

Severity

9.1 (Critical)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-28 20:35 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/plone/plone.app.portlets/secur…	x_refsource_CONFIRM
https://github.com/plone/plone.app.portlets/commi…	x_refsource_MISC
https://github.com/plone/plone.app.portlets/commi…	x_refsource_MISC
https://github.com/plone/plone.app.portlets/commi…	x_refsource_MISC
https://github.com/plone/plone.app.portlets/commi…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
plone	plone.app.portlets	Affected: < 5.0.8 Affected: >= 6.0.0, < 6.0.4 Affected: >= 7.0.0, < 7.0.2	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-55248

Vulnerability from fkie_nvd - Published: 2026-08-28 20:18 - Updated: 2026-08-28 22:16

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/plone/plone.app.portlets/commit/09da52ef7b297daa8e0cfd2361e47c37d9b073ad
	security-advisories@github.com	https://github.com/plone/plone.app.portlets/commit/9f16b6fb10211916686c6c346ea174bf517e3fbd
	security-advisories@github.com	https://github.com/plone/plone.app.portlets/commit/a3b2c2887165b308cd915cbb87b8276f90a76680
	security-advisories@github.com	https://github.com/plone/plone.app.portlets/commit/df5e256baee55083cbd6b9a2623675d4cb26b6cd
	security-advisories@github.com	https://github.com/plone/plone.app.portlets/security/advisories/GHSA-x5g3-w747-2h8q

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "plone.app.portlets",
          "vendor": "plone",
          "versions": [
            {
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            },
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              "version": "\u003e= 6.0.0, \u003c 6.0.4"
            },
            {
              "status": "affected",
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    }
  ],
  "id": "CVE-2026-55248",
  "lastModified": "2026-08-28T22:16:50.527",
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    },
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    },
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}

GHSA-X5G3-W747-2H8Q

Vulnerability from github – Published: 2026-08-28 18:41 – Updated: 2026-08-28 18:41

Summary

plone.app.portlets vulnerable to denial of service via RSS feed portlet

Details

Impact

By adding an RSS portlet, and giving this a link to a very large file, a member can cause a denial of service attack, because Plone will use lots of memory. The member could also use different urls to try to get information about the internal network and open port numbers (SSRF). A malicious RSS feed could cause stored XSS, when the url of a feed item is a javascript url.

Patches

The problem has been patched in plone.app.portlets.

For Plone 6.2: upgrade to plone.app.portlets 7.0.2
For Plone 6.1: upgrade to plone.app.portlets 6.0.4
For Plone 6.0: upgrade to plone.app.portlets 5.0.8

Workarounds

If upgrading is not immediately possible:

Restrict who can manage portlets: remove the plone.app.portlets.ManageOwnPortlets permission from untrusted roles, and limit Manage portlets to trusted administrators (usually this is already restricted to the Manager and Site Administrator roles).
Where the RSS portlet is not needed, unregister it so it cannot be added. This would need to be done by editing a portlets.xml in your own code, so it is not a quick fix.

References

This is similar to this plone.app.event vulnerability. It was discovered by the Plone Security Team by thinking of similar cases to the plone.app.event problem.

Severity

9.1 (Critical)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.0.1"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "plone.app.portlets"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "plone.app.portlets"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.0.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "plone.app.portlets"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.0.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55248"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T18:41:35Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\nBy adding an RSS portlet, and giving this a link to a very large file, a member can cause a denial of service attack, because Plone will use lots of memory. The member could also use different urls to try to get information about the internal network and open port numbers (SSRF). A malicious RSS feed could cause stored XSS, when the url of a feed item is a javascript url.\n\n### Patches\nThe problem has been patched in `plone.app.portlets`.\n\n* For Plone 6.2: upgrade to `plone.app.portlets` 7.0.2\n* For Plone 6.1: upgrade to `plone.app.portlets` 6.0.4\n* For Plone 6.0: upgrade to `plone.app.portlets` 5.0.8\n\n### Workarounds\nIf upgrading is not immediately possible:\n\n- Restrict who can manage portlets: remove the `plone.app.portlets.ManageOwnPortlets` permission from untrusted roles, and limit Manage portlets to trusted administrators (usually this is already restricted to the Manager and Site Administrator roles).\n- Where the RSS portlet is not needed, unregister it so it cannot be added. This would need to be done by editing a `portlets.xml` in your own code, so it is not a quick fix.\n\n### References\n\nThis is similar to this [`plone.app.event` vulnerability](https://github.com/plone/plone.app.event/security/advisories/GHSA-r82h-mqw3-fc56). It was discovered by the Plone Security Team by thinking of similar cases to the `plone.app.event` problem.",
  "id": "GHSA-x5g3-w747-2h8q",
  "modified": "2026-08-28T18:41:35Z",
  "published": "2026-08-28T18:41:35Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/plone/plone.app.portlets/security/advisories/GHSA-x5g3-w747-2h8q"
    },
    {
      "type": "WEB",
      "url": "https://github.com/plone/plone.app.portlets/commit/09da52ef7b297daa8e0cfd2361e47c37d9b073ad"
    },
    {
      "type": "WEB",
      "url": "https://github.com/plone/plone.app.portlets/commit/9f16b6fb10211916686c6c346ea174bf517e3fbd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/plone/plone.app.portlets/commit/a3b2c2887165b308cd915cbb87b8276f90a76680"
    },
    {
      "type": "WEB",
      "url": "https://github.com/plone/plone.app.portlets/commit/df5e256baee55083cbd6b9a2623675d4cb26b6cd"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/plone/plone.app.portlets"
    }
  ],
  "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:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "plone.app.portlets vulnerable to denial of service via RSS feed portlet"
}

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.

Action not permitted

CVE-2026-55248 (GCVE-0-2026-55248)

FKIE_CVE-2026-55248

GHSA-X5G3-W747-2H8Q

Impact

Patches

Workarounds

References

Tags

Sightings

Nomenclature