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Fencer Vulns
high 8.2

CVE-2026-84782 json

DTLS Retransmits Handshake Messages From a Stale Buffer Offset

published 2026-09-29 40 d ago modified 2026-10-08 32 d ago also EUVD-2026-89013

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

Issue summary: The DTLS retransmission logic does not correctly handle a handshake message write that is suspended part-way through. The retransmitted message can be read past the message buffer and the retransmission overwrites the internal state the suspended write needs to resume correctly.

Impact summary: The retransmitted message can disclose a heap memory to the peer as plaintext handshake data or cause a crash and a Denial of Service when the read reaches an unmapped memory region.

CWE: CWE-125: Out-of-bounds Read

Description: DTLS handshake messages can be written out in multiple fragments, and a write can suspend mid-message (returning WANT_WRITE) if the underlying transport temporarily cannot accept more data. While such a write is suspended, the DTLS retransmission timer may independently fire and ask the retransmission logic to resend an earlier, already-acknowledged-as-sent message from its retransmit queue.

The retransmission logic reused the same internal buffer and position tracking as the message that was still being written, without resetting the position back to the start of the message being retransmitted. As a result the retransmission was read starting from wherever the suspended write had left off, producing a mislabelled message whose body was leftover bytes from the other, larger message still in flight - content that was never meant to be sent at that point, and which could run past the end of the allocated buffer.

Separately, even when the retransmission is positioned correctly, allowing it to run to completion while another write is suspended overwrites the same shared bookkeeping that the suspended write depends on to resume. When the application later resumes the suspended write (via a subsequent SSL_read(), SSL_write(), SSL_accept(), or SSL_connect() call), it finds that bookkeeping in a state inconsistent with the message and aborts the process in a debugging build.

The fix resets the retransmission's read position to the start of the message before resending, and skips retransmission entirely whenever a handshake write is still suspended, deferring to the next call that resumes it instead.

FIPS impact: no The affected code is outside the FIPS module boundary.

Patch / fix

  • OpenSSL OpenSSL 1.0.2zs, 1.1.1zj, 3.0.23, 3.4.8, 3.5.9, 3.6.5, 4.0.3
  • openssl Debian 12 3.0.22-1~deb12u2
  • openssl Debian 13 3.5.7-1~deb13u3
  • openssl Debian 14 3.6.5-1

debian advisories DEBIAN-CVE-2026-84782

  • openssl Ubuntu 22.04 LTS 3.0.2-0ubuntu1.30
  • openssl Ubuntu 24.04 LTS 3.0.13-0ubuntu3.16
  • openssl Ubuntu 26.04 LTS 3.5.5-1ubuntu3.6
  • openssl Ubuntu Pro 14.04 LTS 1.0.1f-1ubuntu2.27+esm17
  • openssl Ubuntu Pro 16.04 LTS 1.0.2g-1ubuntu4.20+esm19
  • openssl Ubuntu Pro 18.04 LTS 1.1.1-1ubuntu2.1~18.04.23+esm11
  • openssl Ubuntu Pro 20.04 LTS 1.1.1f-1ubuntu2.24+esm6
  • openssl1.0 Ubuntu Pro 18.04 LTS 1.0.2n-1ubuntu5.13+esm7

ubuntu advisories UBUNTU-CVE-2026-84782

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

  • compat-openssl11 RHEL 9 1:1.1.1k-5.el9_8.6
  • compat-openssl10 RHEL 8 1:1.0.2o-4.el8_10.4
  • openssl RHEL 9 1:3.5.8-2.el9_8
  • openssl-libs RHEL 9 1:3.5.8-2.el9_8
  • openssl-perl RHEL 9 1:3.5.8-2.el9_8
  • openssl RHEL 10.2 1:3.5.8-2.el10_2
  • openssl-libs RHEL 10.2 1:3.5.8-2.el10_2
  • openssl-perl RHEL 10.2 1:3.5.8-2.el10_2

red hat advisories RHSA-2026:80514RHSA-2026:80510RHSA-2026:77396RHSA-2026:76918RHSA-2026:74166RHSA-2026:74162

  • openssl-3-livepatches Linux Micro 6.1 0.7-slfo.1.1_1.1
  • openssl-3 Linux Micro 6.1 3.1.4-slfo.1.1_14.1
  • openssl-3 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 3.5.0-160000.11.1
  • openssl-3 Linux Micro 6.0 3.1.4-159998.1.1
  • openssl-3 SLE Module for Basesystem 15 SP7 3.5.0-150700.5.53.2
  • openssl-3 SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 3.0.8-150400.4.101.1
  • openssl-3 SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 3.0.8-150500.5.80.1
  • openssl-3-livepatches SLE Live Patching 15 SP7 0.7-150700.16.15.1

suse advisories SUSE-SU-2026:24580-1SUSE-SU-2026:24273-1SUSE-SU-2026:24188-1SUSE-SU-2026:24245-1SUSE-SU-2026:24133-1SUSE-SU-2026:4560-1

  • openssl-3 openSUSE Leap 16.0 3.5.0-160000.11.1

opensuse advisories openSUSE-SU-2026:22102-1

  • openssl AlmaLinux 8 1:1.1.1k-18.el8_6
  • openssl-libs AlmaLinux 8 1:1.1.1k-18.el8_6
  • openssl-perl AlmaLinux 8 1:1.1.1k-18.el8_6
  • compat-openssl10 AlmaLinux 8 1:1.0.2o-4.el8_10.4
  • compat-openssl11 AlmaLinux 9 1:1.1.1k-5.el9_8.6
  • openssl AlmaLinux 9 1:3.5.8-2.el9_8
  • openssl-libs AlmaLinux 9 1:3.5.8-2.el9_8
  • openssl-perl AlmaLinux 9 1:3.5.8-2.el9_8

almalinux advisories ALSA-2026:85968ALSA-2026:80510ALSA-2026:80514ALSA-2026:77396ALSA-2026:76918

  • compat-openssl11 Rocky Linux 9 1:1.1.1k-5.el9_8.6
  • compat-openssl10 Rocky Linux 8 1:1.0.2o-4.el8_10.4
  • openssl Rocky Linux 9 1:3.5.8-2.el9_8
  • openssl Rocky Linux 10 1:3.5.8-2.el10_2

rocky linux advisories RLSA-2026:80514RLSA-2026:80510RLSA-2026:77396RLSA-2026:76918

  • openssl Alpine 3.21 3.3.7-r2

alpine advisories ALPINE-CVE-2026-84782

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

  • edk2 Azure Linux 3.0 20240524git3e722403cd16-21
  • openssl Azure Linux 3.0 3.3.7-7

azure linux advisories AZL-105483AZL-105567

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-2026-84782 updated cvss 7.4

openssl: compat-openssl: openssl: Information disclosure via DTLS handshake retransmission

  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-backend-rhel9
    affected: no fix planned “Will not fix”
  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, agent-sandbox/agent-sandbox-router, openshift-sandboxed-containers/osc-podvm-builder-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9 Red Hat Lightspeed Core lightspeed-core/rag-tool-cpu-rhel9, lightspeed-core/rag-tool-cuda-12.9-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9
    affected: no fix available
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/mcp-tools-rhel9, ansible-automation-platform-27/mcp-tools-rhel9, ansible-automation-platform-26/de-minimal-rhel9, ansible-automation-platform-26/ee-minimal-rhel9, ansible-automation-platform-26/lightspeed-rhel9, ansible-automation-platform-27/de-minimal-rhel9, +14 more
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform Ansible Core 2 ansible-automation-platform/ee-minimal-rhel8, ansible-automation-platform/ee-minimal-rhel9, ansible-automation-platform-tech-preview/ee-minimal-rhel8, ansible-automation-platform-tech-preview/ee-minimal-rhel9
    affected: no fix available
  • Red Hat Developer Hub 1 rhdh/rhdh-must-gather-rhel9
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 6 openssl, openssl-perl Red Hat Enterprise Linux 7 ovmf, OVMF, AAVMF, openssl, openssl-libs, openssl-perl Red Hat Enterprise Linux 8 edk2, edk2-ovmf, edk2-aarch64, mingw-openssl, mingw32-openssl, mingw64-openssl Red Hat Enterprise Linux 9 edk2, bootc, edk2-ovmf, glx-utils, edk2-tools, mesa-demos, +12 more Red Hat Enterprise Linux 10 edk2, bootc, rust-sevctl, clevis-pin-tpm2
    affected: no fix available
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9, +1 more
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat Enterprise Linux command line assistant rhel-cla/rhel-knowledge-bridge-rhel10 Red Hat JBoss Core Services jbcs-httpd24-openssl, jbcs-httpd24-openssl-libs, jbcs-httpd24-openssl-perl Red Hat Lightspeed Services for OCP lightspeed-services-ocp/ocp-rules-rhel9 Red Hat Offline Knowledge Portal offline-knowledge-portal/rhokp-rhel9
    affected: no fix available
show 19 more
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-feature-server-rhel9, rhoai/odh-pipelines-components-rhel9, rhoai/odh-ml-pipelines-runtime-generic-rhel9, rhoai/odh-model-registry-job-async-upload-rhel9
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 4 bootupd, rpm-ostree, rust-bootupd, rpm-ostree-libs, openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9 Red Hat OpenStack Platform 16.2 rhosp-rhel8/openstack-base, rhosp-rhel8/openstack-cron, rhosp-rhel8/openstack-etcd, rhosp-rhel8/openstack-redis, rhosp-rhel8/openstack-iscsid, rhosp-rhel8/openstack-ec2-api, +106 more Red Hat Satellite 6 puppet-agent, openvox-agent, satellite/iop-advisor-engine-rhel9 Red Hat Trusted Artifact Signer rhtas/tuffer-rhel9, rhtas/tuftool-rhel9
    affected: no fix available
  • Red Hat Cost Management 4 costmanagement/costmanagement-metrics-rhel9-operator 1793202662
    fixed: vendor fix RHSA-2026:95264
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/gateway-rhel9 1793054375
    fixed: vendor fix RHSA-2026:92856
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/gateway-rhel9 1793172884
    fixed: vendor fix RHSA-2026:92848
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1792593817
    fixed: vendor fix RHSA-2026:88198
  • Red Hat Enterprise Linux AppStream (v. 8) compat-openssl10 1.0.2o-4.el8_10.4
    fixed: vendor fix RHSA-2026:80510
  • Red Hat Enterprise Linux AppStream (v. 9) openssl-perl 3.5.8-2.el9_8, compat-openssl11 1.1.1k-5.el9_8.6
    fixed: vendor fix RHSA-2026:80514
  • Red Hat Enterprise Linux AppStream (v. 10) openssl-perl 3.5.8-2.el10_2
    fixed: vendor fix RHSA-2026:76918
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) compat-openssl11 1.1.1k-4.el9_2.3
    fixed: vendor fix RHSA-2026:89737
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) compat-openssl11 1.1.1k-5.el9_4.4
    fixed: vendor fix RHSA-2026:89736
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) compat-openssl11 1.1.1k-5.el9_6.4
    fixed: vendor fix RHSA-2026:89738
  • Red Hat Enterprise Linux BaseOS (v. 8) openssl 1.1.1k-18.el8_6, openssl-libs 1.1.1k-18.el8_6, openssl-perl 1.1.1k-18.el8_6
    fixed: vendor fix RHSA-2026:85968
  • Red Hat Enterprise Linux BaseOS (v. 9) openssl 3.5.8-2.el9_8, openssl-libs 3.5.8-2.el9_8
    fixed: vendor fix RHSA-2026:77396
  • Red Hat Enterprise Linux BaseOS (v. 10) openssl 3.5.8-2.el10_2, openssl-libs 3.5.8-2.el10_2
    fixed: vendor fix RHSA-2026:76918
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) openssl 1.1.1g-18.el8_4.4, openssl-libs 1.1.1g-18.el8_4.4, openssl-perl 1.1.1g-18.el8_4.4
    fixed: vendor fix RHSA-2026:85970
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) openssl 1.1.1k-18.el8_6, openssl-libs 1.1.1k-18.el8_6, openssl-perl 1.1.1k-18.el8_6
    fixed: vendor fix RHSA-2026:85968
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) openssl 1.1.1g-18.el8_4.4, openssl-libs 1.1.1g-18.el8_4.4, openssl-perl 1.1.1g-18.el8_4.4
    fixed: vendor fix RHSA-2026:85970
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) openssl 1.1.1k-18.el8_6, openssl-libs 1.1.1k-18.el8_6, openssl-perl 1.1.1k-18.el8_6
    fixed: vendor fix RHSA-2026:85968

9 more fixed, 35 more not affected in the full advisory

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
yes
Technical impact
partial
Assessed
40 d ago

Exploit prediction

0.83% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Affected products

  • OpenSSL OpenSSL

Classification

Weakness
Technology feeds

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.