CVE-2026-78680

NLTK versions before 3.10.3 fail to use validated absolute paths when invoking the Graphviz dot binary in dependencygraph.dot2img and AlignedSent._repr_svg_, allowing attackers to execute arbitrary code by placing a malicious dot binary in the search path or current working directory. Attackers can exploit bare-name binary resolution on Windows via the current working directory or on Unix-like systems via relative PATH entries to execute their binary instead of the legitimate Graphviz tool.

CVSS 4.0

8.5CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 7% of CVEs (scores of 2026-10-25)

CWE

CWE-426

Published

2026-08-25

Modified

2026-10-12

Record from

the NVD, synced 2026-10-19

Packages (OSV)

References

• https://github.com/nltk/nltk/security/advisories/GHSA-6hwm-xvph-95vm
• https://www.vulncheck.com/advisories/nltk-before-arbitrary-code-execution-via-graphviz-dot-binary
• https://github.com/nltk/nltk/security/advisories/GHSA-6hwm-xvph-95vm

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