Memory disclosure via short WebSocket mask
Published Jul 14, 2026 · Updated Jul 14, 2026
Buffer over-read in Tornado before 6.5.6 allows remote attackers to disclose process memory through crafted XSRF tokens. The tornado.speedups websocket_mask C function reads four mask bytes unconditionally, so a shorter Python byte string causes a read up to three bytes past its buffer. Exploitation requires xsrf_cookies=True and the optional native extension to be active; exposure is limited to nearby uninitialized process memory.
Summary
What happened
Buffer over-read in Tornado before 6.5.6 allows remote attackers to disclose process memory through crafted XSRF tokens. The tornado.speedups websocket_mask C function reads four mask bytes unconditionally, so a shorter Python byte string causes a read up to three bytes past its buffer. Exploitation requires xsrf_cookies=True and the optional native extension to be active; exposure is limited to nearby uninitialized process memory.
The record
- CVE
- CVE-2026-49854
- Published
- Jul 14, 2026
- Updated
- Jul 14, 2026
- Vendor
- tornadoweb
- Product
- Tornado
- Classifications
- CWE-126, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 14, 2026CVE publishedPublication date reported by the CVE source.
- Jul 14, 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?
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- Affected versionversion=< 6.5.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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