nltk up to 3.9.4 Downloader nltk.downloader.Downloader._download_package weak password hash

Summaryinfo

A vulnerability was found in nltk up to 3.9.4. It has been rated as problematic. Affected by this vulnerability is the function nltk.downloader.Downloader._download_package of the component Downloader. Performing a manipulation results in weak password hash. This vulnerability is cataloged as CVE-2026-12259. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in nltk up to 3.9.4. It has been classified as problematic. This affects the function nltk.downloader.Downloader._download_package of the component Downloader. The manipulation with an unknown input leads to a weak password hash vulnerability. CWE is classifying the issue as CWE-916. The product generates a hash for a password, but it uses a scheme that does not provide a sufficient level of computational effort that would make password cracking attacks infeasible or expensive. This is going to have an impact on confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at huntr.com. This vulnerability is uniquely identified as CVE-2026-12259 since 06/15/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1552 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• nltk

Version

• 3.9.0
• 3.9.1
• 3.9.2
• 3.9.3
• 3.9.4

CPE 2.3info

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CPE 2.2info

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