Answer in brief
CVE-2026-55248 records a Critical severity (CVSS 9.1) vulnerability in plone.app.portlets: Denial of service via RSS feed portlet. The current sources do not mark it as known exploited. The current feed maps plone/plone.app.portlets (generic), plone.app.portlets (pip), plone.app.portlets (pip), plone.app.portlets (pip). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps plone/plone.app.portlets (generic), plone.app.portlets (pip), plone.app.portlets (pip), plone.app.portlets (pip). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| plone/plone.app.portletsgeneric | < 5.0.8 || >= 6.0.0, < 6.0.4 || >= 7.0.0, < 7.0.2 | Not reported |
| plone.app.portletspip | >=7.0.0,<=7.0.1 | 7.0.2 |
| plone.app.portletspip | >=6.0.0,<6.0.4 | 6.0.4 |
| plone.app.portletspip | <5.0.8 | 5.0.8 |
Published upstream
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 28, 2026
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.
Quoted source text, attributed separately from HOL analysis.