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CVE-2025-14009

Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution

10.0 CriticalFix available

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.04%Up 0.6 points since Feb 19, 2026
90%50%10%1%

What each source reports

CVE List 8.8

Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-94, CWE-94
Updated
2026-11-02
EUVDEUVD-2025-207820 8.8

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
EUVD-2025-207820
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-7p94-766c-hgjp 10.0

NLTK has a Zip Slip Vulnerability

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
GHSA-7p94-766c-hgjp
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
NVD 8.8

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
OSVALPINE-CVE-2025-14009 8.8

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
ALPINE-CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
OSV 8.8

Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2025-14009 8.8

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
DEBIAN-CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-7p94-766c-hgjp 10.0

NLTK has a Zip Slip Vulnerability

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
GHSA-7p94-766c-hgjp
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-94
Updated
2026-11-02
OSVPYSEC-2026-96 10.0

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
PYSEC-2026-96
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVROOT-APP-PYPI-CVE-2025-14009 10.0

CVE-2025-14009 in nltk - Patched by Root

Root has patched CVE-2025-14009 in the nltk package for Root:PyPI. Multiple fixed versions available.

Record
ROOT-APP-PYPI-CVE-2025-14009
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2025-14009 8.8

A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary code. The vulnerability arises because NLTK assumes all downloaded packages are trusted and extracts them without validation. If a malicious package contains Python files, such as init.py, these files are executed automatically upon import, leading to remote code execution. This issue can result in full system compromise, including file system access, network access, and potential persistence mechanisms.

Record
UBUNTU-CVE-2025-14009
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.0
10.0 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:10226-1 No score

python311-nltk-3.9.1-3.1 on GA media

These are all security issues fixed in the python311-nltk-3.9.1-3.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:10226-1
Updated
2026-11-02
OSVUSN-8214-1 No score

nltk vulnerability

It was discovered that NLTK incorrectly handled file extraction when opening a maliciously crafted zip file. An attacker could possibly use this issue to create or overwrite files on the system and execute arbitrary code.

Record
USN-8214-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nltk
PyPI
through 3.9.2
3.9.3
py3-nltk
Alpine:v3.24
before 3.9.3-r0
3.9.3-r0
nltk
Debian:12
All versions, plus listed versions
3.10.0-13.10.1-13.10.3-13.8-13.8.1-1
Show 4 moreShow less
3.9.1-13.9.1-23.9.2-13.9.3-1
None known
nltk
Debian:13
All versions, plus listed versions
3.10.0-13.10.1-13.10.3-13.9.1-23.9.2-13.9.3-1
None known
nltk
Debian:14
before 3.9.3-1, plus listed versions
3.9.1-23.9.2-1
3.9.3-1
nltk
PyPI
before 3.9.3, plus listed versions
0.80.90.9.30.9.40.9.5
Show 45 moreShow less
0.9.60.9.70.9.80.9.92.0.12.0.1rc12.0.1rc2-git2.0.1rc32.0.1rc42.0.22.0.32.0.42.0.52.0b42.0b52.0b62.0b72.0b82.0b93.0.03.0.0b13.0.0b23.0.13.0.23.0.33.0.43.0.53.13.23.2.13.2.23.2.33.2.43.2.53.33.43.4.13.4.23.4.33.4.43.4.53.53.5b13.63.6.1
3.9.3
nltk
Root:PyPI
before 3.9.2+aikido.7
3.9.2+aikido.73.9.2+aikido.8
rootio-nltk
Root:PyPI
before 3.9.2+root.io.1
3.9.2+root.io.13.9.2+root.io.23.9.2+root.io.33.9.2+root.io.43.9.2+root.io.5
nltk
Ubuntu:Pro:14.04:LTS
before 2.0~b9-0ubuntu4.1~esm5, plus listed versions
2.0~b9-0ubuntu42.0~b9-0ubuntu4.1~esm22.0~b9-0ubuntu4.1~esm4
2.0~b9-0ubuntu4.1~esm5
nltk
Ubuntu:Pro:16.04:LTS
before 3.1-1ubuntu0.1+esm3, plus listed versions
3.0.4-13.0.5-13.1-13.1-1ubuntu0.13.1-1ubuntu0.1+esm13.1-1ubuntu0.1+esm2
3.1-1ubuntu0.1+esm3
Show 8 moreShow less
Affected packages
PackageAffectedFixed
nltk
Ubuntu:Pro:18.04:LTS
before 3.2.5-1ubuntu0.1+esm3, plus listed versions
3.2.4-13.2.5-13.2.5-1ubuntu0.13.2.5-1ubuntu0.1+esm13.2.5-1ubuntu0.1+esm2
3.2.5-1ubuntu0.1+esm3
nltk
Ubuntu:Pro:20.04:LTS
before 3.4.5-2ubuntu0.1~esm3, plus listed versions
3.4.5-13.4.5-23.4.5-2ubuntu0.1~esm13.4.5-2ubuntu0.1~esm2
3.4.5-2ubuntu0.1~esm3
nltk
Ubuntu:Pro:22.04:LTS
before 3.7-1ubuntu0.1~esm1, plus listed versions
3.5-13.6.5-13.6.7-13.7-1
3.7-1ubuntu0.1~esm1
nltk
Ubuntu:Pro:24.04:LTS
before 3.8.1-1ubuntu0.1~esm1, plus listed versions
3.8.1-1
3.8.1-1ubuntu0.1~esm1
nltk
Ubuntu:25.10
All versions, plus listed versions
3.9.1-2
None known
nltk
Ubuntu:26.10
All versions, plus listed versions
3.9.2-13.9.3-13.10.0-13.10.1-13.10.3-1
None known
nltk
Ubuntu:Pro:26.04:LTS
before 3.9.2-1ubuntu0.1~esm1, plus listed versions
3.9.1-23.9.1-2build13.9.2-1
3.9.2-1ubuntu0.1~esm1
python-nltk
openSUSE:Tumbleweed
before 3.9.1-3.1
3.9.1-3.1

History

History
RecordedChangedSources
affected, aliases, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-14009 is a critical vulnerability (CVSS 10.0) in Nltk, published February 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.04%, the 64th percentile. Fixed in nltk 3.9.3.

References

Show 14 moreShow less
This page doesn't list everything

Left out here: 13 versions. The JSON record has them.

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