Cyber Resilience

CVE-2026-79674

Path Traversal in Nltk ≤ 3.10.3

Public PoCPath Traversal
Published
25 August 2026
Modified
31 August 2026
Patch / advisory
View advisory
CVSS Score v4 8.8
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0023 13th percentile
Risk Priority 43 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-79674 is a high-severity External Control of File Name or Path (CWE-73) vulnerability in Nltk Nltk. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 13th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-3 (Access Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

NLTK versions before 3.10.3 contain a path sandbox bypass vulnerability in corpus-reader constructors that allows attackers to read files outside the intended data root. Attackers can supply arbitrary corpus root paths to LinThesaurusCorpusReader and PanLexLiteCorpusReader constructors to access filesystem content…

more

and SQLite databases outside the pathsec sandbox boundary.

CWE(s)
CWE-73

Related Threats

MITRE ATT&CK Enterprise Techniques

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1083 File and Directory Discovery Discovery
Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1574.007 Path Interception by PATH Environment Variable Stealth
Adversaries may execute their own malicious payloads by hijacking environment variables used to load libraries.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-81726Same product: Nltk Nltk
CVE-2026-62385Same product: Nltk Nltk
CVE-2026-78682Same product: Nltk Nltk
CVE-2026-54293Same product: Nltk Nltk
CVE-2026-79676Same product: Nltk Nltk
CVE-2026-63312Same product: Nltk Nltk
CVE-2026-62384Same product: Nltk Nltk
CVE-2026-79657Same product: Nltk Nltk
CVE-2026-78683Same product: Nltk Nltk
CVE-2026-62388Same product: Nltk Nltk

Affected Assets

nltk
nltk
≤ 3.10.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.3.2

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation directly rejects or sanitizes untrusted path strings before they reach filesystem operations.

AC-3 Access Enforcement partial match

Enforces authorization checks on the actual resource accessed, blocking unauthorized files even when a malicious path is supplied.

AC-6 Least Privilege partial match

Least-privilege limits the set of files or directories any subject can affect, shrinking the blast radius of a path-control flaw.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 partial match
prevents

Least-privilege file authorization directly limits damage from externally controlled paths.

PR.PS-06 partial match
prevents

Secure SDLC practices include input validation and path sanitization that eliminate this weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and path-handling controls that directly prevent external file/path manipulation.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against untrusted input influencing file operations.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles discourage unsafe path construction but do not prescribe concrete file-name controls.

A.8.28 Secure coding partial match
prevents

Secure coding standards require canonicalization, allow-listing, and bounds checks on file paths, directly eliminating CWE-73.

A.8.29 Security testing in development and acceptance partial match
finds

Security testing can detect path-traversal issues but does not itself implement preventive controls.

A.8.3 Information access restriction partial match
mitigates

Information access restriction limits which files can be reached, indirectly reducing impact of path manipulation.

References