Credential disclosure via uncleared reused handles
Published Sep 15, 2026 · Updated Sep 15, 2026
Credential exposure in tornadoweb Tornado before 6.5.7 allows remote attackers to obtain client certificates or proxy credentials. CurlAsyncHTTPClient returns pycurl handles to a pool without resetting them, leaving SSLCERT, SSLKEY, or PROXYUSERPWD values attached to later requests. Exposure requires the optional curl backend, differing per-request credentials on one shared client, handle reuse, and an attacker-controlled or attacker-influenced destination.
Summary
What happened
Credential exposure in tornadoweb Tornado before 6.5.7 allows remote attackers to obtain client certificates or proxy credentials. CurlAsyncHTTPClient returns pycurl handles to a pool without resetting them, leaving SSLCERT, SSLKEY, or PROXYUSERPWD values attached to later requests. Exposure requires the optional curl backend, differing per-request credentials on one shared client, handle reuse, and an attacker-controlled or attacker-influenced destination.
The record
- CVE
- CVE-2026-91992
- Published
- Sep 15, 2026
- Updated
- Sep 15, 2026
- Vendor
- tornadoweb
- Product
- Tornado
- Classifications
- CWE-200, CWE-672
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 15, 2026CVE publishedPublication date reported by the CVE source.
- Sep 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <6.5.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- CurlAsyncHTTPClient client-certificate and proxy-credential demonstrationsproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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