Advisory details:
pypa / nltk/PYSEC-2026-3748
| Advisory ID | pypa/nltk/PYSEC-2026-3748 |
| Aliases |
CVE-2026-78681
GHSA-97qj-x29f-37w7 PYSEC-2026-3748 |
| Summary | 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. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 7.8 |
| Risk | 3.9 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| There are no known CWE. |
| System | Score | Found at |
|---|---|---|
| cvssv4 | 8.7 | https://github.com/pypa/advisory-database/blob/main/vulns/nltk/PYSEC-2026-3748.yaml |
| Reference id | Reference type | URL |
|---|---|---|
| https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7 | ||
| https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtree |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Attack Requirements (AT) | Privileges Required (PR) | User Interaction (UI) | Vulnerable System Impact Confidentiality (VC) | Vulnerable System Impact Integrity (VI) | Vulnerable System Impact Availability (VA) | Subsequent System Impact Confidentiality (SC) | Subsequent System Impact Integrity (SI) | Subsequent System Impact Availability (SA) |
|---|---|---|---|---|---|---|---|---|---|---|
network adjacent local physical |
low high |
none present |
none low high |
none passive active |
high low none |
high low none |
high low none |
high low none |
high low none |
high low none |
There are no SSVC decisions available.