# CVE-2026-19931: Negotiate ambient user conn reuse

CVE-2026-19931 is fixed in curl on 1 platform, first by DEBIAN-CVE-2026-19931, released September 19, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-19931
- Priority: High
- CVSS: 9.8 (Moderate)
- EPSS: 0.0075
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 6, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-19931

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | curl Debian 14 | 8.22.0~rc2-1 | [DEBIAN-CVE-2026-19931](https://patchblox.com/security/data/fix/linux/debian-cve-2026-19931.md) | Sep 19, 2026 |
| Linux | curl sles 15.6 | 8.22.0-150600.4.58.1 | [SUSE-SU-2026:5069-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5069-1.md) | Nov 7, 2026 |
| Linux | curl sles 15.7 | 8.22.0-150700.7.33.1 | [SUSE-SU-2026:5068-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5068-1.md) | Nov 7, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.