CVE-2026-81725
Low
No strong exploitation signal.
CVSS base
3.7
LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS — probability of exploitation (30 days)
0.2%
14.0th percentile
CISA KEV
Not listed
Weakness / dates
CWE-400
Published 2026-08-27 · modified 2026-09-01
CVSS breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
| Attack Vector | N | Network |
| Attack Complexity | H | High |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | N | None |
| Availability | L | Low |
Timeline
- 2026-08-27 — Published (NVD)
- 2026-09-01 — Last modified (NVD)
Description
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.