Vulnerability Intelligence Report
Negotiate ambient user conn reuse
CVE-2026-19931
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.
No Active Exploit Signals
CVSS Base Score
9.8
CRITICAL
Exploitability:3.9
Impact Score:5.9
EPSS Probability:1.16%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
—
Authentication
—
Weaponization
—
SSVC Action
—
Weaknesses (CWE)
CWE-488 ↗Exposure of Data Element to Wrong Session
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| curl | curl | 7.64.1 < 8.14.2 (affected), 8.15.0 < 8.16.1 (affected), 8.17.0 < 8.20.1 (affected), 8.21.0 < 8.22.0 (affected) |
| curl | curl | 6c6035532383e300c712e4c1cd9fdd749ed5cf59 < 7103a93b05bc69ea98ed9d05d02fa9eeba533f2f (affected) |
| curl | curl | 8.21.0 (affected), 8.20.0 (affected), 8.19.0 (affected), 8.18.0 (affected), 8.17.0 (affected), 8.16.0 (affected), 8.15.0 (affected), 8.14.1 (affected), 8.14.0 (affected), 8.13.0 (affected), 8.12.1 (affected), 8.12.0 (affected), 8.11.1 (affected), 8.11.0 (affected), 8.10.1 (affected), 8.10.0 (affected), 8.9.1 (affected), 8.9.0 (affected), 8.8.0 (affected), 8.7.1 (affected), 8.7.0 (affected), 8.6.0 (affected), 8.5.0 (affected), 8.4.0 (affected), 8.3.0 (affected), 8.2.1 (affected), 8.2.0 (affected), 8.1.2 (affected), 8.1.1 (affected), 8.1.0 (affected), 8.0.1 (affected), 8.0.0 (affected), 7.88.1 (affected), 7.88.0 (affected), 7.87.0 (affected), 7.86.0 (affected), 7.85.0 (affected), 7.84.0 (affected), 7.83.1 (affected), 7.83.0 (affected), 7.82.0 (affected), 7.81.0 (affected), 7.80.0 (affected), 7.79.1 (affected), 7.79.0 (affected), 7.78.0 (affected), 7.77.0 (affected), 7.76.1 (affected), 7.76.0 (affected), 7.75.0 (affected), 7.74.0 (affected), 7.73.0 (affected), 7.72.0 (affected), 7.71.1 (affected), 7.71.0 (affected), 7.70.0 (affected), 7.69.1 (affected), 7.69.0 (affected), 7.68.0 (affected), 7.67.0 (affected), 7.66.0 (affected), 7.65.3 (affected), 7.65.2 (affected), 7.65.1 (affected), 7.65.0 (affected), 7.64.1 (affected) |
References & Technical Advisories
No reference links found.
Threat Intelligence Signals
EPSS Score
1.162%
GitHub Advisory
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | curl · Open Source · Sweden |
| Reserved | 2026-08-15T10:35:02 |
| Published | 2026-09-06T17:47:43 |
| Last Updated | 2026-09-15T06:02:51 |
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