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CRITICAL

CVE-2026-19931

CVSS v3

9.8

CRITICAL

EPSS Score

0.7 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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.

Technical details

Published
2026-09-06
Last Modified
2026-09-08

Frequently asked questions

What is 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.

Is CVE-2026-19931 actively exploited?

Active exploitation of CVE-2026-19931 has not been confirmed. Its EPSS score was 0.7% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-19931?

CVE-2026-19931 has a CVSS v3 base score of 9.8 (CRITICAL severity).

Is CVE-2026-19931 affecting your environment?

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