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Fencer Vulns
high 8.1

CVE-2026-86409 json

stale SigV4 headers sent unintended

published 2026-10-20 19 d ago modified 2026-10-29 10 d ago also EUVD-2026-105274

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
0
none known

Summary

Setting `CURLOPT_AWS_SIGV4` to NULL but does not disable SigV4 authentication, contrary to expectations and documentation. A subsequent transfer on the same handle still sends an `Authorization: AWS4-HMAC-SHA256` header to whatever URL isset next, leaking state information.

Patch / fix

  • curl Debian 14 8.22.0-1

debian advisories DEBIAN-CVE-2026-86409

  • 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

ubuntu advisories UBUNTU-CVE-2026-86409

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-2026-86409

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-2026-86409 updated cvss 5.3

curl: curl: stale SigV4 headers sent unintended

  • 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 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 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +8 more Red Hat Enterprise Linux 10 igvm, rust, trustee, s390utils Red Hat Hardened Images rust
    +2 more products
    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 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
no
Technical impact
total
Assessed
10 d ago

Exploit prediction

1.10% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3973135 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

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.