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Fencer Vulns
critical 9.1

CVE-2026-86414 json

leaking host credentials to HTTP proxy

published 2026-10-20 19 d ago modified 2026-10-30 10 d ago also EUVD-2026-105306

cvss
9.1
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 52%
public exploits
0
none known

Summary

An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.

Patch / fix

  • haxx curl 8.14.3, 8.16.2, 8.20.2, 8.23.0
  • curl Ubuntu 22.04 LTS 7.81.0-1ubuntu1.30
  • curl Ubuntu 24.04 LTS 8.5.0-2ubuntu10.16
  • curl Ubuntu 26.10 8.20.0-2ubuntu11.1
  • curl Ubuntu 26.04 LTS 8.18.0-1ubuntu2.8
  • curl Ubuntu Pro 14.04 LTS 7.35.0-1ubuntu2.20+esm24
  • curl Ubuntu Pro 16.04 LTS 7.47.0-1ubuntu2.19+esm21
  • curl Ubuntu Pro 18.04 LTS 7.58.0-2ubuntu3.24+esm15
  • curl Ubuntu Pro 20.04 LTS 7.68.0-1ubuntu2.25+esm10

ubuntu advisories UBUNTU-CVE-2026-86414

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • curl hummingbird 1 8.23.0-0.1.hum1
  • libcurl hummingbird 1 8.23.0-0.1.hum1
  • libcurl-minimal hummingbird 1 8.23.0-0.1.hum1

red hat advisories RHSA-2026:82895

  • 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 8.23.0-1.1

opensuse advisories openSUSE-SU-2026:12150-1

  • curl Alpine 3.24, Alpine 3.23 8.23.0-r0

alpine advisories ALPINE-CVE-2026-86414

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

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-2026-86414 updated cvss 6.5

curl: curl: leaking host credentials to HTTP proxy

  • Red Hat Enterprise Linux 6 curl, libcurl
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 8 curl, libcurl, libcurl-minimal Red Hat Enterprise Linux 9 curl, libcurl, snphost, curl-minimal, libcurl-minimal Red Hat Enterprise Linux 10 curl, snphost Red Hat JBoss Core Services jbcs-httpd24-curl, jbcs-httpd24-libcurl Red Hat Satellite 6 puppet-agent, openvox-agent
    affected: no fix available “Fix deferred”
  • 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 curl 8.23.0-0.1.hum1, libcurl 8.23.0-0.1.hum1, libcurl-minimal 8.23.0-0.1.hum1
    fixed: vendor fix RHSA-2026:82895
  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9 Red Hat Enterprise Linux 8 rls, rust, cargo, clippy, rustfmt, rust-gdb, +8 more Red Hat Enterprise Linux 9 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +8 more Red Hat Enterprise Linux 10 igvm, rust, trustee, s390utils Red Hat Hardened Images rust 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
    +1 more products
    Red Hat Satellite 6 foreman, foreman-cli, foreman-ec2, foreman-gce, foreman-ovirt, foreman-vmware, +9 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
10 d ago

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3993566 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • curl curl

Classification

Weakness
  • CWE-201 Insertion of Sensitive Information Into Sent Data

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.