Bug 2037526 (CVE-2021-3842) - CVE-2021-3842 python-nltk: ReDoS in function get_pos_tagger and malt_regex_tagger
Summary: CVE-2021-3842 python-nltk: ReDoS in function get_pos_tagger and malt_regex_ta...
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-3842
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2037527
Blocks:
TreeView+ depends on / blocked
 
Reported: 2022-01-05 20:09 UTC by Marian Rehak
Modified: 2022-01-05 20:40 UTC (History)
1 user (show)

Fixed In Version:
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Last Closed: 2022-01-05 20:40:46 UTC
Embargoed:

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Description Marian Rehak 2022-01-05 20:09:25 UTC 
nltk is vulnerable to ReDoS attack because of ^-?[0-9]+(.[0-9]+)?$ regex. If attacker succeeds to use malicious payload against RegexpTagger used in function get_pos_tagger and malt_regex_tagger, it will cause a nasty DoS.

External Reference:

https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
Comment 1 Marian Rehak 2022-01-05 20:09:41 UTC 
Created python-nltk tracking bugs for this issue:

Affects: fedora-all [bug 2037527]
Comment 2 Product Security DevOps Team 2022-01-05 20:40:45 UTC 
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.
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