Description
libcurl's TFTP state machine fails to validate state transitions against the
requested transfer direction, accepting opening server responses for both
reads and writes interchangeably. A malicious TFTP server can respond to a
download request in a way that forces the client into transmit mode, prompting
libcurl to consume and transmit data from the handle's persistent
`CURLOPT_READDATA` pointer - including data remaining from unrelated prior
operations, such as an HTTP POST request executed on a reused handle.
Published: 2026-10-20
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
AI Analysis

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Remediation

No solution or workaround provided in the CVE record.

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Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8927-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8932-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8927-2 curl vulnerabilities
History

Tue, 20 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When handling Trivial File Transfer Protocol (TFTP) transfers, a malicious server can trigger information disclosure by responding to a download request in a way that forces the client into transmit mode. Consequently, the client may unintentionally send leftover sensitive data from prior operations on a reused connection handle to the attacker's server. libcurl's TFTP state machine fails to validate state transitions against the requested transfer direction, accepting opening server responses for both reads and writes interchangeably. A malicious TFTP server can respond to a download request in a way that forces the client into transmit mode, prompting libcurl to consume and transmit data from the handle's persistent `CURLOPT_READDATA` pointer - including data remaining from unrelated prior operations, such as an HTTP POST request executed on a reused handle.
Title curl: curl: TFTP direction confusion TFTP direction confusion
References

Sun, 18 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl

Sat, 17 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When handling Trivial File Transfer Protocol (TFTP) transfers, a malicious server can trigger information disclosure by responding to a download request in a way that forces the client into transmit mode. Consequently, the client may unintentionally send leftover sensitive data from prior operations on a reused connection handle to the attacker's server.
Title curl: curl: TFTP direction confusion
Weaknesses CWE-200
References
Metrics threat_severity

None

 cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'}

threat_severity

Low

Subscriptions

Curl Curl
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published:

Updated: 2026-10-20T20:21:45.378Z

Reserved: 2026-09-16T08:12:48.831Z

Link: CVE-2026-92389

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-20T21:17:21.457

Modified: 2026-10-20T21:17:21.457

Link: CVE-2026-92389

cve-icon Redhat

Severity : Low

Publid Date: 2026-10-14T12:00:00Z

Links: CVE-2026-92389 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T22:45:17Z

Weaknesses