Vulnerability in Nltk
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (6.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/nltk/nltk/security/advisories/GHSA-6hwm-xvph-95vm (vendor-advisory)
- www.vulncheck.com/advisories/nltk-before-arbitrary-code-execution-via-graphviz-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-78680?
- CVE-2026-78680 is a high-severity vulnerability in Nltk, classified under Untrusted Search Path. CVSS score: 7.8/10. Published 2026-08-25.
- How severe is CVE-2026-78680?
- High severity. CVSS v3 base score is 7.8 out of 10.