Skip to content
Fencer Vulns
critical 9.8

CVE-2026-19931 json

Negotiate ambient user conn reuse

published 2026-09-06 2 mo ago modified 2026-09-15 55 d ago also EUVD-2026-72166

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

Patch / fix

  • curl curl 8.14.2, 8.16.1, 8.20.1, 8.22.0
  • curl Debian 14 8.22.0~rc2-1

debian advisories DEBIAN-CVE-2026-19931

  • rust hummingbird 1 1.98.0-1.hum1
  • cargo hummingbird 1 1.98.0-1.hum1
  • clippy hummingbird 1 1.98.0-1.hum1
  • rustfmt hummingbird 1 1.98.0-1.hum1
  • rust-gdb hummingbird 1 1.98.0-1.hum1
  • rust-src hummingbird 1 1.98.0-1.hum1
  • rust-lldb hummingbird 1 1.98.0-1.hum1
  • rust-analyzer hummingbird 1 1.98.0-1.hum1

red hat advisories RHSA-2026:63514RHSA-2026:63161

  • curl SLE Module for Basesystem 15 SP7 8.22.0-150700.7.33.1
  • curl SLES 15 SP5-LTSS, SLES 15 SP4-LTSS, SLE Micro 5.5 +8 more 8.14.1-150400.5.98.1
  • curl SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 8.0.1-11.134.1
  • curl SLES for SAP 15 SP6, SLES 15 SP6-LTSS 8.22.0-150600.4.58.1

suse advisories SUSE-SU-2026:5071-1SUSE-SU-2026:5069-1SUSE-SU-2026:5068-1SUSE-SU-2026:4954-1

  • curl openSUSE Tumbleweed 8.22.0-1.1

opensuse advisories openSUSE-SU-2026:11696-1

  • curl Alpine 3.24, Alpine 3.23 8.22.0-r0

alpine advisories ALPINE-CVE-2026-19931

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • curl Azure Linux 3.0 8.11.1-12

azure linux advisories AZL-99752

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-19931 updated cvss 6.5

curl: libcurl: Information disclosure via incorrect connection reuse with Negotiate authentication

  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9 Red Hat Enterprise Linux 9 curl, libcurl, snphost, curl-minimal, libcurl-minimal Red Hat Enterprise Linux 10 curl, igvm, snphost Red Hat Enterprise Linux AI (RHEL AI) 3 rust Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    +1 more products
    Red Hat OpenShift Dev Spaces devspaces/code-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Hardened Images rust 1.98.0-1.hum1, cargo 1.98.0-1.hum1, clippy 1.98.0-1.hum1, curl 8.22.0-0.1.hum1, rustfmt 1.98.0-1.hum1, rust-gdb 1.98.0-1.hum1, +14 more
    fixed: vendor fix RHSA-2026:63514
  • Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 8 curl, libcurl, libcurl-minimal
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 9 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +8 more Red Hat Enterprise Linux 10 rust, trustee, s390utils Red Hat Hardened Images openshell
    not affected: component not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8 Red Hat Satellite 6 foreman, foreman-cli, foreman-ec2, foreman-gce, puppet-agent, foreman-ovirt, +11 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.75% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3923520 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • curl curl

Classification

Weakness
  • CWE-488 Exposure of Data Element to Wrong Session

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.