What is CVE-2026-12259?

CVE-2026-12259 is a medium-severity vulnerability in Nltk Nltk/nltk, classified under Download of Code Without Integrity Check. CVSS score: 5.3/10. Published 2026-08-03.

How severe is CVE-2026-12259?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Nltk Nltk/nltk

CVE-2026-12259

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 t…

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N.

Affected products

Nltk Nltk/nltk — versions unspecified

Weakness classification (CWE)

CWE-494 — Download of Code Without Integrity Check

References

security@huntr.dev

Frequently asked questions

What is CVE-2026-12259?: CVE-2026-12259 is a medium-severity vulnerability in Nltk Nltk/nltk, classified under Download of Code Without Integrity Check. CVSS score: 5.3/10. Published 2026-08-03.
How severe is CVE-2026-12259?: Medium severity. CVSS v3 base score is 5.3 out of 10.