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Fencer Vulns
medium 5.9

CVE-2026-4873 json

connection reuse ignores TLS requirement

published 2026-05-13 5 mo ago modified 2026-09-15 55 d ago also EUVD-2026-29922 , GHSA-5fgw-rv54-prjx , JLSEC-2026-1203

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.

Patch / fix

  • julia CURL_jll 8.20.0+0
  • julia LibCURL_jll 8.20.0+0
  • curl curl 8.14.2, 8.16.1, 8.20.0
  • curl Debian 13 8.14.1-2+deb13u4
  • curl Debian 14 8.20.0~rc2-1

debian advisories DEBIAN-CVE-2026-4873

  • curl Ubuntu 22.04 LTS 7.81.0-1ubuntu1.24
  • curl Ubuntu 24.04 LTS 8.5.0-2ubuntu10.9
  • curl Ubuntu 25.10 8.14.1-2ubuntu1.3
  • curl Ubuntu 26.04 LTS 8.18.0-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2026-4873

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 8.20.0-0.1.hum1
  • libcurl hummingbird 1 8.20.0-0.1.hum1
  • libcurl-minimal hummingbird 1 8.20.0-0.1.hum1

red hat advisories RHSA-2026:12916

  • 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 8.14.1-160000.6.1
  • curl-mini SLES for SAP applications 16.0, SLES 16.0 8.14.1-160000.6.1
  • curl SLES LTSS Extended Security 12 SP5 8.0.1-11.123.1

suse advisories SUSE-SU-2026:2925-1SUSE-SU-2026:2703-1SUSE-SU-2026:22146-1SUSE-SU-2026:22156-1

  • curl openSUSE Leap 16.0 8.14.1-160000.6.1
  • curl openSUSE Tumbleweed 8.20.0-1.1

opensuse advisories openSUSE-SU-2026:20973-1openSUSE-SU-2026:10674-1

  • curl Alpine 3.21 8.14.1-r3
  • curl Alpine 3.22 8.14.1-r4
  • curl Alpine 3.24, Alpine 3.23 8.20.0-r0

alpine advisories ALPINE-CVE-2026-4873

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 8.11.1-7
  • cmake Azure Linux 3.0 3.30.3-14

azure linux advisories AZL-86658AZL-86685

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-2026-4873 updated cvss 5.3

curl: curl: Information disclosure due to incorrect TLS connection reuse

  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, openshift-sandboxed-containers/osc-rhel9-operator, openshift-sandboxed-containers/osc-operator-bundle, openshift-sandboxed-containers/osc-podvm-builder-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9, confidential-compute-attestation-tech-preview/trustee-rhel9 Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9, openshift-logging/fluentd-rhel9, openshift-logging/eventrouter-rhel9, openshift-logging/logging-view-plugin-rhel9, openshift-logging/cluster-logging-rhel9-operator, openshift-logging/log-file-metric-exporter-rhel9, +1 more 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, rust, cargo, clippy, libcurl, rustfmt, +14 more
    +6 more products
    Red Hat Enterprise Linux 10 curl, rust, snphost, trustee, s390utils, trustee-guest-components Red Hat Enterprise Linux AI (RHEL AI) 3 rust Red Hat JBoss Core Services curl Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9 Red Hat Trusted Profile Analyzer rhtpa/rhtpa-trustification-service-rhel9
    affected: workaround, 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 8.20.0-0.1.hum1, libcurl 8.20.0-0.1.hum1, libcurl-minimal 8.20.0-0.1.hum1
    fixed: vendor fix RHSA-2026:12916
  • 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
    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
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/3621851 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
OSV 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
julia CURL_jll
<8.20.0+0
8.20.0+0
julia LibCURL_jll
<8.20.0+0
8.20.0+0

Affected products

  • curl curl

Classification

Weakness
  • CWE-319 Cleartext Transmission of Sensitive Information
  • 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.