MEDIUMUnknown →
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 declarat
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
No package-level mapping for this advisory.
Exploit signal
- Known exploited (CISA KEV)
- No
- EPSS score
- —
- EPSS percentile
- —
EPSS is the probability a CVE is exploited in the wild; percentile is its rank among all CVEs.
Sources
- https://www.cve.org/CVERecord?id=CVE-2026-78681
- https://github.com/cveproject/cvelistv5/tree/main/cves/2026/78xxx/cve-2026-78681.json
- https://github.com/nltk/nltk/security/advisories/ghsa-97qj-x29f-37w7
- https://nvd.nist.gov/vuln/detail/cve-2026-78681
- https://www.vulncheck.com/advisories/nltk-before-entity-expansion-dos-via-elementtree
Structured record: https://ubuntu.com/security/CVE-2026-78681
Recommended response stack
Snyk — Scan your dependencies in CI and fix this vulnerability.→Socket — Detect malicious and compromised packages before they ship.→
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