CVE Intelligence
Low File handling

CVE-2026-71514 — NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass

NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader. _load_lang_ngrams joins the corpus root with crubadan_code, the column-0 value read from the corpus table.txt mapping file, and opens the result with the builtin open() rather than the pathsec-validated opener, so os.path.join discards the root when that value is absolute and the read escapes the corpus directory without the containment check nltk.pathsec applies when ENFORCE is set. An attacker who controls a corpus package can disclose file contents outside the corpus root through lang_freq, limited to paths ending in -3grams.txt whose contents parse as token count lines.

Published Aug 22, 2026 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: VulnCheck

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.17%
ahead of 6% of scored CVEs · Oct 15, 2026
Affects
Nltk
Nltk
CVSS base
3.3
Low · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — github.com (NIST National Vulnerability Database)
  • Documented patch — github.com (NIST National Vulnerability Database)
  • Pip Nltk: fixed in version 3.10.3 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Nltk Nltk, Pip Nltk).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  4. Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Nltk Nltk ≥ 3.9.4 and ≤ 3.10.2 Vulnerable NIST National Vulnerability Database
Nltk Nltk ≥ 3.9.4 and < 3.10.3 Vulnerable CVE Program (cve.org) e CISA ADP
Pip Nltk ≥ 3.9.4 and < 3.10.3 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
2.0 CVSS 4.0 Low — — disclosure@vulncheck.com via NIST National Vulnerability Database
2.0 CVSS 4.0 Low — — VulnCheck via CVE Program (cve.org) e CISA ADP
3.3 CVSS 3.1 Low 1.8 1.4 nvd@nist.gov via NIST National Vulnerability Database
2.5 CVSS 3.1 Low 1.0 1.4 disclosure@vulncheck.com via NIST National Vulnerability Database
2.5 CVSS 3.1 Low — — GitHub, Inc. via GitHub Security Advisories
2.5 CVSS 3.1 Low — — VulnCheck via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 3.3 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

EPSS over time FIRST

Oct 14, 2026 → Oct 15, 2026 · 2 reading(s) · max 0.17%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Monitor file creation in web directories and paths with traversal sequences (../).
endpoint telemetry (EDR)file integrity (FIM)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 14, 2026 · GitHub Security Advisories
  • Affected products added · pip/nltk
    Oct 14, 2026 · GitHub Security Advisories
  • Affected products added · nltk/nltk
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 14, 2026
  • Fix documented
    Oct 14, 2026 · NIST National Vulnerability Database
  • Affected products added · nltk/nltk
    Oct 14, 2026 · NIST National Vulnerability Database
  • CVSS changed · 3.3
    Oct 14, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 14, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 14, 2026 · Alertas do Telegram
  • CVE published
    Aug 22, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 14, 2026 – Oct 14, 2026
  • 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

7 on the record

Elsewhere on this site

Nltk
every CVE for this vendor
File handling
same class
CWE-22
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-109956 NLTK through 3.10.3 Path Traversal via WekaClassifier Model Path 2d
  • CVE-2026-81725 NLTK before 3.10.3 Regular Expression Denial of Service via Pl196xCorpusReader Aug 27, 2026
  • CVE-2026-81726 NLTK through 3.10.3 Path Traversal via Model-Artifact APIs Aug 27, 2026
  • CVE-2026-81724 NLTK before 3.10.3 Denial of Service via Uncontrolled Recursion Aug 27, 2026
  • CVE-2026-81727 NLTK before 3.10.3 Hardlink File Overwrite via downloader Aug 27, 2026
  • CVE-2026-81722 nltk PorterStemmer before 3.10.3 Quadratic-time DoS Aug 27, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-71514 is "NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass", rated Low. It affects Nltk (Nltk); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.3 describes technical severity. EPSS 0.17% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.