Description
A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given
hostname using Negotiate authentication, when the initial request is done
using empty credentials. This can make user B's request get sent over user A's
previously authenticated connection.
Published: 2026-09-06
Score: 9.8 Critical
EPSS: 1.2% Low
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Wed, 16 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-613
References
Metrics threat_severity

None

 threat_severity

Moderate

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl

Tue, 08 Sep 2026 19:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-269
CWE-668

Tue, 08 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-488
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

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

Sun, 06 Sep 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Weaknesses CWE-269
CWE-668
Vendors & Products Curl
Curl curl

Sun, 06 Sep 2026 18:00:00 +0000

Type Values Removed Values Added
Description A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials. This can make user B's request get sent over user A's previously authenticated connection.
Title Negotiate ambient user conn reuse
References

Subscriptions

Curl Curl
Haxx Curl
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published:

Updated: 2026-09-15T06:02:51.009Z

Reserved: 2026-08-15T10:35:02.789Z

Link: CVE-2026-19931

cve-icon Vulnrichment

Updated: 2026-09-08T15:42:38.212Z

cve-icon NVD

Status : Modified

Published: 2026-09-06T18:17:20.733

Modified: 2026-09-15T07:16:27.290

Link: CVE-2026-19931

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-06T17:47:43Z

Links: CVE-2026-19931 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-10T04:00:06Z

Weaknesses