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DEBIAN-CVE-2026-72818

Type: advisorySource: OSV1 source record

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]+(?:[.\-][a-z0-9]+)* 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.

Announced Source revision 1
Original source ↗

DEBIAN-CVE-2026-72818

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:DEBIAN-CVE-2026-72818

nltk

Source reference: /affected/0/package/name

Affected versions
3.10.0-1

Source reference: /affected/0/versions

3.10.1-1

Source reference: /affected/0/versions

3.10.3-1

Source reference: /affected/0/versions

3.8-1

Source reference: /affected/0/versions

3.8.1-1

Source reference: /affected/0/versions

3.9.1-1

Source reference: /affected/0/versions

3.9.1-2

Source reference: /affected/0/versions

3.9.2-1

Source reference: /affected/0/versions

3.9.3-1

Source reference: /affected/0/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

nltk

Source reference: /affected/1/package/name

Affected versions
3.10.0-1

Source reference: /affected/1/versions

3.10.1-1

Source reference: /affected/1/versions

3.10.3-1

Source reference: /affected/1/versions

3.9.1-2

Source reference: /affected/1/versions

3.9.2-1

Source reference: /affected/1/versions

3.9.3-1

Source reference: /affected/1/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

nltk

Source reference: /affected/2/package/name

Affected versions
3.10.0-1

Source reference: /affected/2/versions

3.10.1-1

Source reference: /affected/2/versions

3.9.1-2

Source reference: /affected/2/versions

3.9.2-1

Source reference: /affected/2/versions

3.9.3-1

Source reference: /affected/2/versions

Fixed versions
3.10.3-1

Source reference: /affected/2/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          }
        ]
      }
    ],
    "package": {
      "name": "nltk",
      "purl": "pkg:deb/debian/nltk?arch=source&distro=bookworm",
      "ecosystem": "Debian:12"
    },
    "versions": [
      "3.10.0-1",
      "3.10.1-1",
      "3.10.3-1",
      "3.8-1",
      "3.8.1-1",
      "3.9.1-1",
      "3.9.1-2",
      "3.9.2-1",
      "3.9.3-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-72818.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          }
        ]
      }
    ],
    "package": {
      "name": "nltk",
      "purl": "pkg:deb/debian/nltk?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "3.10.0-1",
      "3.10.1-1",
      "3.10.3-1",
      "3.9.1-2",
      "3.9.2-1",
      "3.9.3-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-72818.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "3.10.3-1"
          }
        ]
      }
    ],
    "package": {
      "name": "nltk",
      "purl": "pkg:deb/debian/nltk?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "3.10.0-1",
      "3.10.1-1",
      "3.9.1-2",
      "3.9.2-1",
      "3.9.3-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-72818.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#15028 · Revision 1
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Publisher date
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