{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","favicon":"https://feed.craftedsignal.io/favicon-32x32.png","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-63312/feed.json","home_page_url":"https://feed.craftedsignal.io/","icon":"https://feed.craftedsignal.io/apple-touch-icon.png","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[{"cvss":7.1,"id":"CVE-2026-63310"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["NLTK (\u003c 3.9.3)","NLTK (\u003c 3.10.0)","nltk (\u003c 3.9.4)"],"_cs_severities":["high"],"_cs_tags":["cve-2026-63312","path-traversal","library-vulnerability","python"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eNLTK (Natural Language Toolkit) versions before 3.9.3 contain a security flaw (CVE-2026-63310) in the downloader module. The library fails to perform integrity checks on packages after they are downloaded and before they are extracted. This vulnerability exposes users to potential remote code execution if an attacker can position themselves to intercept network traffic. By leveraging techniques such as man-in-the-middle (MitM) positioning or DNS poisoning, an attacker can substitute legitimate NLTK model packages with malicious archives. Because the library lacks validation of these downloaded files, it will proceed to extract and process the contents, potentially leading to the execution of attacker-supplied code on the host machine. This affects all users running vulnerable versions of NLTK across Windows, Linux, and macOS.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker performs reconnaissance to identify users or automated systems initiating NLTK package downloads.\u003c/li\u003e\n\u003cli\u003eAttacker establishes a MitM position on the network or poisons local DNS records to intercept requests to NLTK package servers.\u003c/li\u003e\n\u003cli\u003eAttacker intercepts the HTTP/HTTPS request initiated by the NLTK downloader module.\u003c/li\u003e\n\u003cli\u003eAttacker forces the NLTK client to download a spoofed, malicious package file.\u003c/li\u003e\n\u003cli\u003eNLTK downloader module completes the file transfer.\u003c/li\u003e\n\u003cli\u003eNLTK automatically proceeds to extract the malicious package contents without verifying cryptographic signatures or file hashes.\u003c/li\u003e\n\u003cli\u003eExtracted malicious payloads are executed by the NLTK library or the parent application process.\u003c/li\u003e\n\u003cli\u003eAttacker achieves arbitrary code execution on the target host.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability allows for arbitrary code execution in the context of the user or process running the NLTK library. Given the widespread use of NLTK in data science, machine learning, and natural language processing pipelines, this could result in unauthorized data access, system compromise, and lateral movement within the affected environment.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpdate the NLTK library to version 3.9.3 or later across all development and production environments.\u003c/li\u003e\n\u003cli\u003eAudit network traffic for unauthorized redirection or interception, specifically targeting traffic destined for NLTK package repositories.\u003c/li\u003e\n\u003cli\u003eImplement TLS interception or inspection where possible to identify malicious payload delivery during the download phase.\u003c/li\u003e\n\u003cli\u003eMonitor for unexpected process spawns from the parent application process responsible for NLTK package management.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-08-22T15:31:45Z","date_published":"2026-08-22T15:31:26Z","id":"https://feed.craftedsignal.io/briefs/2026-08-nltk-integrity-vulnerability/","summary":"NLTK versions prior to 3.9.3 fail to verify package integrity after download, allowing remote attackers to perform MitM or DNS poisoning attacks to inject and execute arbitrary code.","title":"NLTK Downloader Module Integrity Vulnerability","url":"https://feed.craftedsignal.io/briefs/2026-08-nltk-integrity-vulnerability/"}],"language":"en","title":"CraftedSignal Threat Feed - Cve-2026-63312","version":"https://jsonfeed.org/version/1.1"}