Resource exhaustion in Tornadoweb Tornado
CVE-2026-91990
Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (36.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.004 · change: -0.001
Affected products
Weakness classification (CWE)
References
- github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq (vendor-advisory)
- www.vulncheck.com/advisories/tornado-before-6.5.8-memory-amplification-dos-via-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-91990?
- CVE-2026-91990 is a high-severity vulnerability in Tornadoweb Tornado, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-15.
- How severe is CVE-2026-91990?
- High severity. CVSS v3 base score is 7.5 out of 10.