CVE-2026-81723
NLTK before 3.10.3 Quadratic CPU Exhaustion via XMLCorpusView
Reported by vulncheck · Published August 27, 2026
nltk is fixed in 3.10.3 (PyPI)
NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView._read_xml_fragment() that rescans accumulated XML fragments on every 1 KiB block read. Attackers can provide malformed XML corpus files to cause severe CPU consumption and denial of service through affected readers like BNCCorpusReader.
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| nltk | PyPI | 3.10.3 |
| open-webui | Wolfi | 0.11.3-r1 |
| open-webui | Chainguard | 0.11.3-r1 |
| nemo | Chainguard | 2.7.3-r27 |
| nltk | nltk | 3.10.3 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| nltk | nltk | 0, 3.10.3 |
| wolfi | open-webui | 0 |
| nltk | nltk | 0, 3.10.3 |
| chainguard | open-webui | 0 |
| PyPI | nltk | 0 |
| chainguard | nemo | 0 |
Timeline
- Aug 27, 2026 CVE Published
- Aug 28, 2026 EPSS Score (18 in total, the first dated here)
- Sep 2, 2026 Security Advisory
Query this with the API
The same record, from the CLI:
vulnetix vdb vuln CVE-2026-81723
vulnetix vdb fixes CVE-2026-81723Or with curl, using the org id and key from your account page:
curl -s -H "Authorization: ApiKey ${VULNETIX_ORG_ID}:${VULNETIX_API_KEY}" \
"https://api.vdb.vulnetix.com/v2/vuln/CVE-2026-81723/fixes/registry"The Community plan is free and allows 50 queries a day. Get a free API key · API quickstart
References
- GitHub Security Advisory (GHSA-vp2x-qp44-57v7) vendor-advisory
- VulnCheck Advisory: NLTK before 3.10.3 Quadratic CPU Exhaustion via XMLCorpusView third-party-advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-81723 advisory
- https://github.com/advisories/GHSA-vp2x-qp44-57v7 advisory
- https://github.com/nltk/nltk/commit/7808692d451b962711005d954859bb83aabcf8fa patch
- https://github.com/nltk/nltk/releases/tag/v3.10.3 url