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Fencer Vulns
high 7.5

CVE-2026-12064 json

proto-default skips SSH verification

published 2026-07-03 4 mo ago modified 2026-09-15 55 d ago also EUVD-2026-41502 , GHSA-jm94-9f7h-36pr , JLSEC-2026-1202

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.

Patch / fix

  • julia CURL_jll 8.21.0+0
  • julia LibCURL_jll 8.21.0+0
  • curl curl 8.14.2, 8.16.1, 8.20.1
  • curl Debian 14 8.21.0~rc3-1

debian advisories DEBIAN-CVE-2026-12064

  • curl Ubuntu 25.10 8.14.1-2ubuntu1.5
  • curl Ubuntu 26.04 LTS 8.18.0-1ubuntu2.3

ubuntu advisories UBUNTU-CVE-2026-12064

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 RHEL 10.2 8.12.1-4.el10_2.3
  • libcurl RHEL 10.2 8.12.1-4.el10_2.3
  • libcurl-minimal RHEL 10.2 8.12.1-4.el10_2.3
  • curl hummingbird 1 8.21.0-0.1.hum1
  • libcurl hummingbird 1 8.21.0-0.1.hum1
  • libcurl-minimal hummingbird 1 8.21.0-0.1.hum1
  • rust hummingbird 1 1.96.1-1.hum1
  • cargo hummingbird 1 1.96.1-1.hum1

red hat advisories RHSA-2026:72506RHSA-2026:55450RHSA-2026:29017RHSA-2026:34975

  • curl SLE Module for Basesystem 15 SP7 8.22.0-150700.7.33.1
  • curl Linux Micro 6.1 8.14.1-slfo.1.1_8.1
  • curl SLES 15 SP5-LTSS, SLES 15 SP4-LTSS, SLE Micro 5.5 +8 more 8.14.1-150400.5.86.1
  • curl Linux Micro 6.0 8.14.1-7.1
  • curl SLE Module for Basesystem 15 SP7 8.14.1-150700.7.20.1
  • curl SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 8.14.1-160000.8.1
  • curl-mini SLES for SAP applications 16.0, SLES 16.0 8.14.1-160000.8.1
  • curl SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 8.0.1-11.134.1

suse advisories SUSE-SU-2026:5071-1SUSE-SU-2026:5069-1SUSE-SU-2026:5068-1SUSE-SU-2026:22889-1SUSE-SU-2026:3043-1SUSE-SU-2026:22709-1

  • curl openSUSE Tumbleweed 8.21.0-1.1
  • curl openSUSE Leap 16.0 8.14.1-160000.8.1

opensuse advisories openSUSE-SU-2026:11230-1openSUSE-SU-2026:21272-1

  • curl Alpine 3.23 8.22.0-r0
  • curl Alpine 3.24 8.21.0-r0

alpine advisories ALPINE-CVE-2026-12064

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 8.11.1-10

azure linux advisories AZL-91812

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-2026-12064 updated cvss 7.5

curl: curl: SSH host verification bypass when using schemeless URLs with SFTP/SCP

  • Red Hat Enterprise Linux AppStream (v. 10) libcurl-devel 8.12.1-4.el10_2.3, curl-debuginfo 8.12.1-4.el10_2.3, curl-debugsource 8.12.1-4.el10_2.3, libcurl-debuginfo 8.12.1-4.el10_2.3, libcurl-minimal-debuginfo 8.12.1-4.el10_2.3
    fixed: vendor fix RHSA-2026:55450
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) libcurl-devel 8.12.1-1.el10_0.10, curl-debuginfo 8.12.1-1.el10_0.10, curl-debugsource 8.12.1-1.el10_0.10, libcurl-debuginfo 8.12.1-1.el10_0.10, libcurl-minimal-debuginfo 8.12.1-1.el10_0.10
    fixed: vendor fix RHSA-2026:72506
  • Red Hat Enterprise Linux BaseOS (v. 10) curl 8.12.1-4.el10_2.3, libcurl 8.12.1-4.el10_2.3, libcurl-minimal 8.12.1-4.el10_2.3
    fixed: vendor fix RHSA-2026:55450
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) curl 8.12.1-1.el10_0.10, libcurl 8.12.1-1.el10_0.10, libcurl-minimal 8.12.1-1.el10_0.10
    fixed: vendor fix RHSA-2026:72506
  • Red Hat Hardened Images rust 1.96.1-1.hum1, cargo 1.96.1-1.hum1, clippy 1.96.1-1.hum1, curl 8.21.0-0.1.hum1, rustfmt 1.96.1-1.hum1, rust-gdb 1.96.1-1.hum1, +14 more
    fixed: vendor fix RHSA-2026:34975
  • Red Hat JBoss Core Services 2.4.62.SP5
    fixed: vendor fix RHSA-2026:56869
  • Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 8 curl, libcurl, libcurl-minimal Red Hat Enterprise Linux 9 curl, libcurl, curl-minimal, libcurl-minimal
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    not affected: vulnerable code not in execute path
show 1 more
  • Red Hat OpenShift Dev Spaces devspaces/code-rhel9 Red Hat Trusted Profile Analyzer rhtpa/rhtpa-trustification-service-rhel9
    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
partial
Assessed
4 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3797526 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
julia CURL_jll
<8.21.0+0
8.21.0+0
julia LibCURL_jll
>=7.81.0+0, <8.21.0+0
8.21.0+0

Affected products

  • curl curl

Classification

Weakness
  • CWE-297 Improper Validation of Certificate with Host Mismatch
  • CWE-295 Improper Certificate Validation

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.