CVE-2026-126298
NLTK before 3.10.4 contains a denial of service vulnerability in Tree.chomsky_normal_form that allows remote attackers to exhaust CPU through quadratic-time right-factor binarization using list.pop(0). Attackers can supply a wide flat treebank tree parsed by Tree.fromstring to force tens of seconds of single-threaded CPU consumption, blocking the processing thread.
- Score
- 8.7 high
- Published
- 2026-11-13
- Links
- NVD · cve.org · Report wrong data
Matched ports (1)
| Port | Package | Version | Status | Maintainer |
|---|---|---|---|---|
| textproc/py-nltk | py312-nltk | 3.10.0,2 | unaddressed | demon@FreeBSD.org |
Template for a VuXML entry
Check the version numbers before you commit this entry. Some ports share an entry in the CVE database with another port, such as sqlite2 and sqlite3. The version shown here may then be one that never existed for this port.
Ranges per package from the CVE rows that match this port, in pkg notation with the port's epoch and revision, every bound checked with pkg; one range per epoch the port actually had. make newentry in security/vuxml creates the vid.
<vuln vid="FIXME (make newentry)">
<topic>py312-nltk -- FIXME</topic>
<affects>
<package>
<name>py312-nltk</name>
<range><lt>3.10.4,2</lt></range>
</package>
</affects>
<description>
<body xmlns="http://www.w3.org/1999/xhtml">
<p>CVE-2026-126298: NLTK before 3.10.4 contains a denial of service
vulnerability in Tree.chomsky_normal_form that allows remote
attackers to exhaust CPU through quadratic-time right-factor
binarization using list.pop(0). Attackers can supply a wide flat
treebank tree parsed by Tree.fromstring to force tens of seconds of
single-threaded CPU consumption, blocking the processing thread.</p>
</body>
</description>
<references>
<cvename>CVE-2026-126298</cvename>
<url>https://nvd.nist.gov/vuln/detail/CVE-2026-126298</url>
</references>
<dates>
<discovery>2026-11-13</discovery>
<entry>2026-11-13</entry>
</dates>
</vuln>