CVE-2026-5773libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers.
Updated under an hour ago ()
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It affects haxx curl. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-488, CWE-918
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
haxx curl haxx:curl | from 7.40.0 before 8.20.0 | NVD |
References
- https://curl.se/docs/CVE-2026-5773.htmlpatch, vendor-advisory
- https://curl.se/docs/CVE-2026-5773.jsonvendor-advisory
- https://hackerone.com/reports/3650689exploit, issue-tracking, third-party-advisory
- http://www.openwall.com/lists/oss-security/2026/04/29/9mailing-list, patch, third-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.