Operation on a Resource after Expiration or Release Affecting tornado package, versions [,6.5.7)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-TORNADO-17356157
- published17 Jun 2026
- disclosed15 Jun 2026
- creditKoh Jun Sheng
Introduced: 15 Jun 2026
CVE-2026-91992 (opens in a new tab)How to fix?
Upgrade tornado to version 6.5.7 or higher.
Overview
tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
Affected versions of this package are vulnerable to Operation on a Resource after Expiration or Release in the CurlAsyncHTTPClient, where per-request credentials such as client TLS certificates or proxy authentication details are not properly cleared when reusing handles across requests. An attacker can obtain sensitive credentials intended for a previous request by triggering a subsequent request to a different host or proxy, causing the credentials to be sent to an unintended recipient.
Note: This is only exploitable if the application uses the optional CurlAsyncHTTPClient backend and is configured in a manner that matches the affected proxy-related usage patterns. Applications using the default SimpleAsyncHTTPClient backend are not affected, as it does not support proxies.