CVE-2026-5545

6.5 MEDIUM
Published: May 13, 2026 Modified: May 13, 2026
View on NVD

Description

libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host. 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 request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. An application that first uses Negotiate authentication to a server with `user1:password1` and then does another operation to the same server asking for any authentication method but for `user2:password2` (while the previous connection is still alive) - the second request gets confused and wrongly reuses the same connection and sends the new request over that connection thinking it uses a mix of user1's and user2's credentials when it is in fact still using the connection authenticated for user1...

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://curl.se/docs/CVE-2026-5545.html
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Patch Vendor Advisory
https://curl.se/docs/CVE-2026-5545.json
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Vendor Advisory
https://hackerone.com/reports/3642555
Source: 2499f714-1537-4658-8207-48ae4bb9eae9
Exploit Issue Tracking Third Party Advisory
https://hackerone.com/reports/3642555
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Issue Tracking Third Party Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.4%
28th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

haxx