PYSEC-2026-3748

vendorUSosv

view advisory published 2026-08-25Licence: CC-BY-4.0

NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.

describes (1)

Related CVEs.

ID	severity	EPSS	exploitable	published
CVE-2026-78681US	high7.5	0.52% (44th)	—	2026-08-25
NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nes…

references

External citations — patches, advisories, analysis.

https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7EVIDENCE
https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtreeADVISORY

scry

Advisories like this name the exposed products attackers go after on your perimeter. See what is exposed on your perimeter with a free passive scan.

Free scan