Tornado: Out-of-bounds memory access in C extension

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49854
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-14 21:17:02 UTC
Updated2026-07-15 19:50:11 UTC
DescriptionTornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS: 0.004500000 probability, percentile 0.363830000 (date 2026-07-19)

Problem Types: CWE-126 | CWE-126 CWE-126: Buffer Over-read

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tornadoweb Tornado affected < 6.5.6 Not specified

References

ReferenceSourceLinkTags
github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9 [email protected] github.com
github.com/tornadoweb/tornado/releases/tag/v6.5.6 [email protected] github.com
github.com/tornadoweb/tornado/pull/3626 [email protected] github.com
github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a... [email protected] github.com
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