Tornado: Event loop blocking and excess memory use from chunked bodies with many small chunks

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0038, the 32nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

1. 31 Oct 2026, 14:07 UTC First seen by agentprime
2. 31 Oct 2026, 14:07 UTC Confirmed by OSV

Sources

• GitHub Advisory Database: GHSA-r4j5-9xpp-3985
• OSV: GHSA-r4j5-9xpp-3985
• github.com/tornadoweb/tornado/security/advisories/GHSA-r4j5-9xpp-3985
• nvd.nist.gov/vuln/detail/CVE-2026-115927
• github.com/tornadoweb/tornado/pull/3773
• github.com/tornadoweb/tornado/commit/ceab33581489751a66fba8566ad6d5960d4b01c8
• github.com/tornadoweb/tornado
• github.com/tornadoweb/tornado/releases/tag/v6.6.0

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.