CVE-2026-71514: NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader

Routine

LOW 2.5UPGRADE

CVE-2026-71514 is a low-severity flaw (CVSS 2.5) affecting nltk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 a

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	2.5 (Low)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-22
Published	2026-08-22
Last modified	2026-10-14

Publisher (CNA): VulnCheck · Vendor: nltk

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-22 14:16 UTCPublished CVE record published
2026-10-14 19:10 UTCUpdated Record last modified

nltk nltk UPGRADE

Affected: >= 3.9.4 and <= 3.10.2

Fixed in: newer than 3.10.2

Safe to downgrade to: a release before 3.9.4

1. Check installed version

apt-cache policy nltk || rpm -q nltk || nltk --version

2. UPGRADE to newer than 3.10.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nltk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nltk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.9.4 (Debian / Ubuntu)

apt-cache madison nltk sudo apt install nltk=<VERSION_BEFORE_3.9.4> sudo apt-mark hold nltk

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nltk sudo dnf downgrade nltk-<VERSION_BEFORE_3.9.4> sudo dnf versionlock add nltk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-71514?

nltk: upgrade to newer than 3.10.2. Exact commands for each OS are on this page.

Is CVE-2026-71514 being exploited?

CVE-2026-71514 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-71514 affect?

CVE-2026-71514 affects nltk. Severity is low (CVSS 2.5). 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

How urgent is CVE-2026-71514?

Priority 10/100. No elevated risk signals yet.

Related CVEs

CVE-2026-12252 HIGH 7.8 UPGRADE In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes (StanfordPOSTagger, StanfordNERTagger
CVE-2026-12259 MEDIUM 6.5 DOWNGRADE In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes downloaded package
CVE-2026-12261 MEDIUM 6.5 UPGRADE A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and mode
CVE-2026-12372 LOW 3.7 DOWNGRADE A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the current develop
CVE-2026-71513 HIGH 8.8 UPGRADE NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only th

References

← Back to latest CVEs