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Fencer Vulns
critical 9.1

CVE-2026-8927 json

env-set cross-proxy Digest auth state leak

published 2026-07-03 4 mo ago modified 2026-09-15 55 d ago also EUVD-2026-41508 , GHSA-jr4f-4564-w3mr , JLSEC-2026-1216

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

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 13 8.14.1-2+deb13u7
  • curl Debian 14 8.21.0~rc2-1

debian advisories DEBIAN-CVE-2026-8927

  • curl Ubuntu 22.04 LTS 7.81.0-1ubuntu1.25
  • curl Ubuntu 24.04 LTS 8.5.0-2ubuntu10.10
  • curl Ubuntu 25.10 8.14.1-2ubuntu1.4
  • curl Ubuntu 26.04 LTS 8.18.0-1ubuntu2.2
  • curl Ubuntu Pro 14.04 LTS 7.35.0-1ubuntu2.20+esm20
  • curl Ubuntu Pro 16.04 LTS 7.47.0-1ubuntu2.19+esm16
  • curl Ubuntu Pro 18.04 LTS 7.58.0-2ubuntu3.24+esm9
  • curl Ubuntu Pro 20.04 LTS 7.68.0-1ubuntu2.25+esm4

ubuntu advisories UBUNTU-CVE-2026-8927

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 9 7.76.1-40.el9_8.7
  • libcurl RHEL 9 7.76.1-40.el9_8.7
  • curl-minimal RHEL 9 7.76.1-40.el9_8.7
  • libcurl-minimal RHEL 9 7.76.1-40.el9_8.7
  • curl RHEL 10.2 8.12.1-4.el10_2.4
  • libcurl RHEL 10.2 8.12.1-4.el10_2.4
  • libcurl-minimal RHEL 10.2 8.12.1-4.el10_2.4
  • curl hummingbird 1 8.21.0-0.1.hum1

red hat advisories RHSA-2026:72506RHSA-2026:69126RHSA-2026:55432RHSA-2026:29017RHSA-2026:34975

  • 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 for SAP 15 SP6, SLES 15 SP6-LTSS 8.14.1-150600.4.46.1

suse advisories SUSE-SU-2026:22889-1SUSE-SU-2026:3043-1SUSE-SU-2026:22709-1SUSE-SU-2026:2926-1SUSE-SU-2026:2925-1SUSE-SU-2026:22553-1

  • 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 AlmaLinux 8 7.61.1-34.el8_10.18
  • libcurl AlmaLinux 8 7.61.1-34.el8_10.18
  • libcurl-minimal AlmaLinux 8 7.61.1-34.el8_10.18
  • curl AlmaLinux 9 7.76.1-40.el9_8.7
  • libcurl AlmaLinux 9 7.76.1-40.el9_8.7
  • curl-minimal AlmaLinux 9 7.76.1-40.el9_8.7
  • libcurl-minimal AlmaLinux 9 7.76.1-40.el9_8.7
  • curl AlmaLinux 10 8.12.1-4.el10_2.4

almalinux advisories ALSA-2026:92368ALSA-2026:69126ALSA-2026:55432

  • curl Rocky Linux 8 7.61.1-34.el8_10.18
  • curl Rocky Linux 9 7.76.1-40.el9_8.7
  • curl Rocky Linux 10 8.12.1-4.el10_2.4

rocky linux advisories RLSA-2026:92368RLSA-2026:69126RLSA-2026:55432

  • curl Alpine 3.21 8.14.1-r3
  • curl Alpine 3.22 8.14.1-r4
  • curl Alpine 3.23 8.22.0-r0
  • curl Alpine 3.24 8.21.0-r0

alpine advisories ALPINE-CVE-2026-8927

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
  • cmake Azure Linux 3.0 3.30.3-15

azure linux advisories AZL-91788AZL-91833

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-2026-8927 updated cvss 7.5

curl: Information disclosure due to uncleared proxy authentication state

  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 6 curl, libcurl
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 9 snphost Red Hat Enterprise Linux 10 snphost Red Hat Enterprise Linux AI (RHEL AI) 3 rust
    affected: workaround, no fix available
  • Red Hat JBoss Core Services libcurl.so
    affected: workaround, no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20 cert-manager/cert-manager-operator-rhel9 1790272426, cert-manager/cert-manager-operator-rhel9 1790589855, cert-manager/jetstack-cert-manager-rhel9 1790223279, cert-manager/jetstack-cert-manager-rhel9 1790589912, cert-manager/cert-manager-istio-csr-rhel9 1790223719, cert-manager/cert-manager-istio-csr-rhel9 1790589914, +1 more
    fixed: vendor fix RHSA-2026:72475
  • Red Hat Enterprise Linux AppStream (v. 9) libcurl-devel 7.76.1-40.el9_8.7, curl-debuginfo 7.76.1-40.el9_8.7, curl-debugsource 7.76.1-40.el9_8.7, libcurl-debuginfo 7.76.1-40.el9_8.7, curl-minimal-debuginfo 7.76.1-40.el9_8.7, libcurl-minimal-debuginfo 7.76.1-40.el9_8.7
    fixed: vendor fix RHSA-2026:69126
  • Red Hat Enterprise Linux AppStream (v. 10) libcurl-devel 8.12.1-4.el10_2.4, curl-debuginfo 8.12.1-4.el10_2.4, curl-debugsource 8.12.1-4.el10_2.4, libcurl-debuginfo 8.12.1-4.el10_2.4, libcurl-minimal-debuginfo 8.12.1-4.el10_2.4
    fixed: vendor fix RHSA-2026:55432
show 16 more
  • 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 AppStream EUS (v.9.6) libcurl-devel 7.76.1-31.el9_6.4, curl-debuginfo 7.76.1-31.el9_6.4, curl-debugsource 7.76.1-31.el9_6.4, libcurl-debuginfo 7.76.1-31.el9_6.4, curl-minimal-debuginfo 7.76.1-31.el9_6.4, libcurl-minimal-debuginfo 7.76.1-31.el9_6.4
    fixed: vendor fix RHSA-2026:93454
  • Red Hat Enterprise Linux BaseOS (v. 8) curl 7.61.1-34.el8_10.18, libcurl 7.61.1-34.el8_10.18, libcurl-minimal 7.61.1-34.el8_10.18
    fixed: vendor fix RHSA-2026:92368
  • Red Hat Enterprise Linux BaseOS (v. 9) curl 7.76.1-40.el9_8.7, libcurl 7.76.1-40.el9_8.7, curl-minimal 7.76.1-40.el9_8.7, libcurl-minimal 7.76.1-40.el9_8.7
    fixed: vendor fix RHSA-2026:69126
  • Red Hat Enterprise Linux BaseOS (v. 10) curl 8.12.1-4.el10_2.4, libcurl 8.12.1-4.el10_2.4, libcurl-minimal 8.12.1-4.el10_2.4
    fixed: vendor fix RHSA-2026:55432
  • 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 Enterprise Linux BaseOS EUS (v.9.6) curl 7.76.1-31.el9_6.4, libcurl 7.76.1-31.el9_6.4, curl-minimal 7.76.1-31.el9_6.4, libcurl-minimal 7.76.1-31.el9_6.4
    fixed: vendor fix RHSA-2026:93454
  • 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 OpenShift Dev Spaces 3.30 devspaces/code-rhel9 1790619703
    fixed: vendor fix RHSA-2026:73516
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1790241954, rhui5/rhua-rhel9 1790242004, rhui5/haproxy-rhel9 1790241900, rhui5/installer-rhel9 1790241922, rhui5/cds-kubernetes-rhel9 1790241897
    fixed: vendor fix RHSA-2026:71603
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20 cert-manager/jetstack-cert-manager-acmesolver-rhel9 1790223630
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 9 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +9 more
    not affected: component not present
  • Red Hat Enterprise Linux 10 igvm, rust, trustee, s390utils, trustee-guest-components Red Hat OpenShift AI (RHOAI) rhoai/odh-llama-stack-k8s-operator-rhel9
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    not affected: component not present
  • Red Hat OpenShift Dev Spaces 3.30 devspaces/udi-rhel9 1790369528, devspaces/server-rhel9 1790625554, devspaces/openvsx-rhel9 1790616590, devspaces/traefik-rhel9 1790615456, devspaces/udi-base-rhel9 1790366977, devspaces/code-sshd-rhel9 1790618567, +9 more 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 ICSA-26-293-05 updated cvss 5.3

Hitachi Energy RTU500 Product

  • Hitachi Energy RTU500 series CMU Firmware vers:RTU500_series_CMU_Firmware/>=13.5.1, <=13.5.4, vers:RTU500_series_CMU_Firmware/>=13.6.1, <=13.6.3, vers:RTU500_series_CMU_Firmware/>=13.7.1, <=13.7.8, vers:RTU500_series_CMU_Firmware/>=13.8.1, <=13.8.2
    affected: vendor fix, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3744543 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
OSV 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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
<8.21.0+0
8.21.0+0

Affected products

  • curl curl

Classification

Weakness
  • CWE-294 Authentication Bypass by Capture-replay

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.