CVE-2026-54293
NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Proc…
Impact
NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Prior to 3.10.0-rc1, nltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK's SECURITY.md and read arbitrary files from the filesystem. While literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path. This vulnerability is fixed in 3.10.0-rc1.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | nltk | <= 3.9.4 | 3.10.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nltk | Nltk | before 3.10.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-p4gq-832x-fm9v
- https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v
- https://nvd.nist.gov/vuln/detail/CVE-2026-54293
- https://github.com/nltk/nltk/pull/3575
- https://access.redhat.com/security/cve/CVE-2026-54293
- https://bugzilla.redhat.com/show_bug.cgi?id=2491486
- https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-2078.yaml
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json
- https://access.redhat.com/errata/RHSA-2026:42644
- https://access.redhat.com/errata/RHSA-2026:60520
- https://access.redhat.com/errata/RHSA-2026:65126