High severity · published May 13, 2026
CVE-2026-5773
wrong reuse of SMB connection
7.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 49% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CU
curl · curl
7.40.0 before 8.14.2; 8.15.0 before 8.16.1; 8.17.0 before 8.20.0; aec2e865f06669b9cb5d26cc1148d70bc418b163 before 74a169575d6412dc0ff532acdf94de35a6c2a571; 8.19.0; 8.18.0; +34 more · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-5773
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-5773
Patch
https://curl.se/docs/CVE-2026-5773.html
Vendor Advisory
https://curl.se/docs/CVE-2026-5773.json
Exploit
https://hackerone.com/reports/3650689
Mailing List
http://www.openwall.com/lists/oss-security/2026/04/29/9
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