high7.5
CVE-2026-78681
NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs.
Impact
NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | nltk | <= 3.10.2 | 3.10.3 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nltk | Nltk | before 3.10.3 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-97qj-x29f-37w7
- https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7
- https://nvd.nist.gov/vuln/detail/CVE-2026-78681
- https://github.com/nltk/nltk/commit/e91789c9a043296ad04912ce171c22776d45963b
- https://github.com/nltk/nltk/releases/tag/v3.10.3
- https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3748.yaml
- https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtree