PYPI · SEPTEMBER 2026 · EARLY WARNING

NLTK PyPI Package SSRF Vulnerability: Early Warning

Q: Am I affected?

You are affected if your project uses NLTK versions from 3.8 down to 2.0.1rc1.

Q: What should I do right now?

Upgrade to NLTK version 3.10.3 or later to mitigate the vulnerability.

Q: Has this been exploited in the wild?

There are no reports of this vulnerability being exploited in the wild as of the latest information.

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.

Severity: HIGH
Affected component: nltk (pypi)
Affected versions: >= 3.8, <= 3.8 or >= 3.7, <= 3.7 or >= 3.6.7, <= 3.6.7 or >= 3.6.6, <= 3.6.6 or >= 3.6.5, <= 3.6.5 or >= 3.6.2, <= 3.6.2 or >= 3.6.1, <= 3.6.1 or >= 3.6, <= 3.6 or >= 3.5, <= 3.5 or >= 3.5b1, <= 3.5b1 or >= 3.4.4, <= 3.4.4 or >= 3.4.3, <= 3.4.3 or >= 3.4.1, <= 3.4.1 or >= 3.4, <= 3.4 or >= 3.3, <= 3.3 or >= 3.2.5, <= 3.2.5 or >= 3.2.4, <= 3.2.4 or >= 3.2.3, <= 3.2.3 or >= 3.2.2, <= 3.2.2 or >= 3.2.1, <= 3.2.1 or >= 3.2, <= 3.2 or >= 3.1, <= 3.1 or >= 3.0.5, <= 3.0.5 or >= 3.0.4, <= 3.0.4 or >= 3.0.3, <= 3.0.3 or >= 3.0.2, <= 3.0.2 or >= 3.0.0b1, <= 3.0.0b1 or >= 3.0a4, <= 3.0a4 or >= 2.0.1rc4, <= 2.0.1rc4 or >= 2.0.1rc3, <= 2.0.1rc3 or >= 2.0.1rc2, <= 2.0.1rc2 or >= 2.0.1rc1, <= 2.0.1rc1
Patched version: 3.10.3

CVE-2024-39705CVE-2026-33236GHSA-3GQM-FCW5-W839

An SSRF vulnerability has been reported in the NLTK package on PyPI. Users of affected versions are advised to upgrade.

What happened

An SSRF vulnerability has been identified in the NLTK package on PyPI. The vulnerability lies in the validate_network_url() function, which fails open when DNS resolution returns an error, potentially allowing SSRF attacks on cloud metadata endpoints. This issue is tracked under CVE-2024-39705, CVE-2026-33236, and GHSA-3GQM-FCW5-W839. The vulnerability affects a wide range of NLTK versions, from 3.8 down to 2.0.1rc1.

To assess your exposure, check if your project or dependencies include any of the affected NLTK versions. The vulnerability has not been exploited in the wild as of the latest reports, but it is recommended to take preventive action by upgrading to a patched version.

What to do about it

Upgrade to NLTK version 3.10.3 or later to mitigate the SSRF vulnerability.
Review your project dependencies to ensure no affected NLTK versions are in use.
Monitor the primary sources for any updates or additional information on the vulnerability.

How 0Day would have caught this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If nltk is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

Frequently asked questions

Am I affected?

You are affected if your project uses NLTK versions from 3.8 down to 2.0.1rc1.

What should I do right now?

Upgrade to NLTK version 3.10.3 or later to mitigate the vulnerability.

Has this been exploited in the wild?

There are no reports of this vulnerability being exploited in the wild as of the latest information.

Sources

Join the 0Day waitlist →

← Back to all threats