Bug 2515531 (CVE-2026-73643) - CVE-2026-73643 js-yaml: js-yaml: Denial of Service via exponential parsing in flow collections
Summary: CVE-2026-73643 js-yaml: js-yaml: Denial of Service via exponential parsing in...
Keywords:
Status: NEW
Alias: CVE-2026-73643
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-13 18:27 UTC by OSIDB Bzimport
Modified: 2026-08-17 20:24 UTC (History)
168 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-13 18:27:16 UTC
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.


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