CVE-2026-19931

critical

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.

References

https://hackerone.com/reports/3923520

https://curl.se/docs/CVE-2026-19931.json

https://curl.se/docs/CVE-2026-19931.html

Details

Source: Mitre, NVD

Published: 2026-09-06

Updated: 2026-09-15

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 9.8

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: Critical

EPSS

EPSS: 0.00259