{
  "cveId": "CVE-2026-72818",
  "url": "https://patchblox.com/security/cve/CVE-2026-72818",
  "summary": "CVE-2026-72818 is fixed in nltk on 1 platform by DEBIAN-CVE-2026-72818 (version 3.10.3-1), released August 21, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "nltk: The URLS regular expression in nltk/tokenize/casual.py, compiled into TweetTokenizer.WORD_RE and applied by TweetToke...",
  "description": "The URLS regular expression in nltk/tokenize/casual.py, compiled into TweetTokenizer.WORD_RE and applied by TweetTokenizer.tokenize, contains a naked-domain branch whose domain-label prefix [a-z0-9]\u002B(?:[.\\-][a-z0-9]\u002B)* is unbounded. Input consisting of many alternating label separators can be partitioned in exponentially many ways, and because the branch also requires a trailing top-level domain that such input never supplies, the engine explores those partitions before failing at each offset. A few kilobytes of input therefore consumes seconds to minutes of single-threaded CPU, and the HANG_RE substitution performed before matching does not collapse the pattern. TweetTokenizer is intended for tokenizing untrusted social-media text, so any service that applies it, or the module-level casual_tokenize, to submitted text can be stalled per request without authentication. Version 3.10.1 bounds the label repetition.",
  "published": "2026-08-20T22:18:05Z",
  "severity": "",
  "epss": 0.00742,
  "epssPercentile": 0.54953,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "nltk",
      "release": "Debian 14",
      "fixedVersion": "3.10.3-1",
      "fix": "DEBIAN-CVE-2026-72818",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-72818",
      "released": "2026-08-21T23:37:15Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-10T01:44:33Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}