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CVE-2026-5773

⚠️ high
🔍 Scan for this CVE
Summary

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 subsequen

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 Score
7.5
High
EPSS Score
0.6
Exploit Probability
Published Date
2026-05-13
First Seen: 2026-09-16
📊 Relative Risk Intelligence

This CVE is Moderate Risk - more severe than 67.9% of all 357,695 vulnerabilities in our database.

#114,979
Above average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: May 13, 2026
🔍 Exploitation Status
Poc
Proof-of-concept available
⚙️ Automatable
YES
Can be exploited automatically
💥 Technical Impact
Partial
Limited system impact
🏆 Discovered By
Osama Hamad Daniel Stenberg (remediation developer)
SSVC data provided by CISA
Last Modified 2026-09-15
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE IDs (Weakness Types)
CWE-488 CWE-918

📦 Affected Products 1

Vendor Product Status Affected Versions
haxx curl Affected
> 7.40.0 < 8.20.0

🔗 References 4

https://curl.se/docs/CVE-2026-5773.html
Patch Vendor Advisory
https://curl.se/docs/CVE-2026-5773.json
Vendor Advisory
https://hackerone.com/reports/3650689
Exploit Issue Tracking Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/04/29/9
Mailing List Patch Third Party Advisory

🔗 Related CVEs 6

CVE ID Severity CVSS EPSS Summary Published
CVE-2026-13608 ⚠️ high 7.4 0.6 A flaw in the libcurl SASL negotiation for LDAP authentication allows an incomplete handshake sequence to be misinterpre... 2026-09-06
CVE-2026-18924 ⛔ critical 9.1 0.9 A flaw in libcurl's handling of HTTP/2 Server Push streams, when the parent handle is set to share connections with othe... 2026-09-06
CVE-2026-19931 ⛔ critical 9.8 1.2 A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, w... 2026-09-06
CVE-2026-80229 ⚠️ high 7.5 0.9 When performing transfers via libcurl’s multi interface, pooled TLS connections can outlive their originating easy han... 2026-09-06
CVE-2026-80230 ⚠️ high 7.5 0.6 When `CURLOPT_PINNEDPUBLICKEY` is configured alongside options that disable standard peer verification (`CURLOPT_SSL_VER... 2026-09-06
CVE-2026-80231 ⚠️ high 7.5 0.9 A flaw in libcurl makes it wrongly reuse an existing HTTPS connection setup for a given hostname even when using a diffe... 2026-09-06
These CVEs affect the same products