DEBIAN-CVE-2026-81725
NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the read_block method through public APIs like words() and tagged_words() to force repeated rescans and achieve near-quadratic runtime growth.
DEBIAN-CVE-2026-81725
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-2026-81725
nltk
Source reference: /affected/0/package/name
- Affected versions
- 3.10.0-1
Source reference:
/affected/0/versions3.10.1-1Source reference:
/affected/0/versions3.10.3-1Source reference:
/affected/0/versions3.8-1Source reference:
/affected/0/versions3.8.1-1Source reference:
/affected/0/versions3.9.1-1Source reference:
/affected/0/versions3.9.1-2Source reference:
/affected/0/versions3.9.2-1Source reference:
/affected/0/versions3.9.3-1Source 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/versions3.10.1-1Source reference:
/affected/1/versions3.10.3-1Source reference:
/affected/1/versions3.9.1-2Source reference:
/affected/1/versions3.9.2-1Source reference:
/affected/1/versions3.9.3-1Source 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/versions3.10.1-1Source reference:
/affected/2/versions3.9.1-2Source reference:
/affected/2/versions3.9.2-1Source reference:
/affected/2/versions3.9.3-1Source 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-2026-81725.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-2026-81725.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-2026-81725.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #58370 · Revision 1
- Added to Heist Feed
- Publisher date