Bug 2521342 (CVE-2026-66393) - CVE-2026-66393 nltk: NLTK: Denial of Service via unbounded recursion in JSONTaggedDecoder
Summary: CVE-2026-66393 nltk: NLTK: Denial of Service via unbounded recursion in JSONT...
Keywords:
Status: NEW
Alias: CVE-2026-66393
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-22 14:32 UTC by OSIDB Bzimport
Modified: 2026-08-31 07:23 UTC (History)
19 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-22 14:32:17 UTC 
NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() that allows attackers to cause denial of service by supplying deeply nested JSON structures. Attackers can craft JSON payloads exceeding the recursion limit to trigger an unhandled RecursionError that crashes the Python process.
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