{"id":"CVE-2026-54293","aliases":["GHSA-p4gq-832x-fm9v","PYSEC-2026-2078"],"url":"https://o3.security/vulnerability/CVE-2026-54293","summary":"NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read","details":"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.","published":"2026-06-22T17:25:05.611Z","modified":"2026-07-23T03:56:11.930977983Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.00555,"percentile":0.43264,"asOf":"2026-08-10"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"nltk","fixedVersion":"3.10.0"}],"fix":{"url":"https://github.com/nltk/nltk/pull/3575","label":"nltk/nltk#3575"},"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:42644"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-54293"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54293.json"},{"type":"ADVISORY","url":"https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54293"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2491486"},{"type":"FIX","url":"https://github.com/nltk/nltk/pull/3575"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-23T03:56:11.930977983Z"}}