CVE-2026-54293: high-severity vulnerability in nltk
NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
nltk · nltkRelated CVEs — nltk
In the same product, most dangerous first.
CVE-2021-43854HIGHInefficient Regular Expression Complexity in nltkEPSS 2.8%CVE-2026-79657CRITICALNLTK before 3.10.3 Remote Code Execution via Unsafe Pickle DeserializationEPSS 1.3%CVE-2026-33231HIGHNLTK has unauthenticated remote shutdown in nltk.app.wordnet_appEPSS 1.3%CVE-2026-71513HIGHNLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name BypassEPSS 1.1%CVE-2026-79675CRITICALNLTK before 3.10.3 JVM Argument Injection via Per-Call OptionsEPSS 0.8%CVE-2026-72818HIGHNLTK TweetTokenizer URL Pattern Backtracks Catastrophically on Naked-Domain-Like InputEPSS 0.7%
References
https://access.redhat.com/errata/RHSA-2026:42644https://access.redhat.com/errata/RHSA-2026:60520https://access.redhat.com/errata/RHSA-2026:65126https://access.redhat.com/security/cve/CVE-2026-54293https://bugzilla.redhat.com/show_bug.cgi?id=2491486https://github.com/nltk/nltk/pull/3575https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9vhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json