cvedb.io
CVE-2026-12259
MEDIUM · CVSS 5.3
EPSS exploitation probability: 0%
Published 2026-08-03T08:17:17.880 · Last modified 2026-08-03T08:17:17.880

Summary

In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes downloaded package bytes to disk and may extract them before enforcing SHA-256 or MD5 checksum validation. This allows an attacker to tamper with the package response body for `info.url` through a compromised mirror, malicious proxy, or other source-substitution condition, leading to the installation of attacker-controlled package bytes. The vulnerability can result in malicious corpus or model content being trusted by downstream users or applications.

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.