CVE-2026-19931CWE-488

CVE-2026-19931

Critical · published September 6, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
54.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00747 · 54.3th percentile
Weakness
CWE-488 · Exposure of Data Element to Wrong Session
Published
2026-09-06T22:17Z
Affected products (1)
ProductVersionsFixed in
haxx/curl≥ 7.64.1, < 8.22.08.22.0
References (4)
EPSS history
Timeline
  • 08 SEP 03:22Z
    EPSS moved — → 0%
    epss
  • 06 SEP 17:47Z
    Negotiate ambient user conn reuse
    cvelistv5