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Vulnerabilities CVE-2026-58486

CVE-2026-58486

High
Open
TLP:CLEAR

HedgeDoc: Denial-of-service via YAML alias expansion in note frontmatter

NVD CVE.org
Critical Infrastructure

AI Analysis

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Description

HedgeDoc is an open source, real-time, collaborative, markdown notes application. Prior to version 1.11.0, HedgeDoc was vulnerable to a YAML alias bomb due to unsafe processing of the note frontmatter. HedgeDoc parsed frontmatter with js-yaml.load (js-yaml v3) via @hedgedoc/meta-marked, which resolved YAML anchor aliases. A compact malicious payload could therefore expand into a huge object structure, consuming excessive CPU. This expansion ran on every request to the publish view (/s/<shortid>) and, when placed under the opengraph key, the editor view (/<noteId>). A ten-level alias bomb could block the single Node.js event loop for roughly 235 seconds per request, causing concurrent requests to hang or drop and rendering the instance unavailable (DoS). Because the note was stored in the database, the impact survived process restarts until the note was removed. toobusy-js did not reliably mitigate the worst cases, as the event loop was saturated before the middleware could respond. This issue was fixed in version 1.11.0.

Details

CVSS Score
8.3
EPSS Score
0.24%

14.6th percentile

CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
Confidence
90%
Published
Jul 13, 2026
Last Modified
Jul 13, 2026
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