CVE-2026-92389

TFTP direction confusion

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Published Oct 20, 2026 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

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
Type Values Removed Values Added
Metrics 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'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}
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
Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl
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
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Oct 30, 2026, 12:19 PM
Reserved
Sep 16, 2026, 8:12 AM

View source JSON

Updated
Oct 30, 2026, 12:17 PM

JSON

Status
Awaiting Analysis
Published
Oct 20, 2026, 9:17 PM
Modified
Oct 30, 2026, 1:20 PM

View source JSON

Severity
Low
Public date
Oct 14, 2026, 12:00 PM

View source Bugzilla JSON

Updated
Oct 30, 2026, 3:00 PM

JSON