CVE-2026-5773

wrong reuse of SMB connection

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Published May 13, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
libcurl might in some circumstances reuse the wrong connection for SMB(S)
transfers.

libcurl features a pool of recent connections so that subsequent requests can
reuse an existing connection to avoid overhead.

When reusing a connection a range of criteria must be met. Due to a logical
error in the code, a network transfer operation that was requested by an
application could wrongfully reuse an existing SMB connection to the same
server that was using a different "share" than the new subsequent transfer
should.

This could in unlucky situations lead to the download of the wrong file or the
upload of a file to the wrong place. When this happens, the same credentials
are used and the server name is the same.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8227-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-8525-1 curl vulnerabilities
History
Type Values Removed Values Added
Description libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a network transfer operation that was requested by an application could wrongfully reuse an existing SMB connection to the same server that was using a different 'share' than the new subsequent transfer should. This could in unlucky situations lead to the download of the wrong file or the upload of a file to the wrong place. When this happens, the same credentials are used and the server name is the same. libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a network transfer operation that was requested by an application could wrongfully reuse an existing SMB connection to the same server that was using a different "share" than the new subsequent transfer should. This could in unlucky situations lead to the download of the wrong file or the upload of a file to the wrong place. When this happens, the same credentials are used and the server name is the same.
Weaknesses CWE-488
Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
Weaknesses CWE-918
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

 ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}
Type Values Removed Values Added
References
Type Values Removed Values Added
Description A flaw was found in libcurl. Due to a logical error in the connection reuse mechanism for SMB (Server Message Block) transfers, libcurl might reuse an existing SMB connection with a different share than intended. This vulnerability, categorized as CWE-488 (Exposure of Data Element to Wrong Session), could lead to the download of an incorrect file or the upload of a file to an unintended location when an application uses libcurl for SMB transfers. libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a network transfer operation that was requested by an application could wrongfully reuse an existing SMB connection to the same server that was using a different 'share' than the new subsequent transfer should. This could in unlucky situations lead to the download of the wrong file or the upload of a file to the wrong place. When this happens, the same credentials are used and the server name is the same.
Title curl: libcurl: Wrong file transfer due to incorrect SMB connection reuse wrong reuse of SMB connection
References
Type Values Removed Values Added
First Time appeared Curl
Curl libcurl
Vendors & Products Curl
Curl libcurl
Type Values Removed Values Added
Description A flaw was found in libcurl. Due to a logical error in the connection reuse mechanism for SMB (Server Message Block) transfers, libcurl might reuse an existing SMB connection with a different share than intended. This vulnerability, categorized as CWE-488 (Exposure of Data Element to Wrong Session), could lead to the download of an incorrect file or the upload of a file to an unintended location when an application uses libcurl for SMB transfers.
Title curl: libcurl: Wrong file transfer due to incorrect SMB connection reuse
Weaknesses CWE-1025
References
Metrics threat_severity

None

 cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

threat_severity

Moderate
Earlier changes (2)
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Sep 15, 2026, 6:03 AM
Reserved
Apr 8, 2026, 6:51 AM

View source JSON

Updated
May 13, 2026, 9:05 AM

JSON

Status
Modified
Published
May 13, 2026, 1:01 PM
Modified
Nov 11, 2026, 8:10 PM

View source JSON

Severity
Moderate
Public date
Apr 29, 2026, 12:00 AM

View source Bugzilla JSON

Updated
Sep 21, 2026, 8:00 AM

JSON