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Fencer Intel
high 7.5

CVE-2026-54876 json

Client-Side Memory Leak in OCSP Response Checking

published 3mo ago modified 3d ago also EUVD-2026-53385

cvss
7.5
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 42%
public exploits
0
none known

Summary

Issue summary: A malicious TLS server can cause a memory leak in a TLS client that has enabled OCSP response checking by sending an OCSP response that contains no single response entries.

Impact summary: An attacker can leak an attacker-tunable amount of memory per TLS handshake in a victim client application. A long-running client that repeatedly connects to a malicious server can have its memory exhausted, resulting in a Denial of Service.

CWE: CWE-401: Missing Release of Memory after Effective Lifetime

Description: The affected function is called during X.509 certificate chain verification when OCSP response checking is enabled with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL verification flags, for example when a TLS client verifies an OCSP response stapled into the TLS handshake by the server.

When the received BasicOCSPResponse contains an empty SEQUENCE OF SingleResponse, which is permitted on the wire and accepted by the OpenSSL decoder, the OCSP_BASICRESP structure allocated by OCSP_response_get1_basic() was not freed because an early return bypassed the cleanup code at the end of the function.

The amount of memory leaked per handshake can be amplified by the attacker by padding the certs field of the BasicOCSPResponse with bogus certificates, which are parsed and stored in the leaked structure before the empty response check triggers the early return. A long-running TLS client that repeatedly connects to a malicious server can have its memory exhausted over time.

OCSP response checking is not enabled by default. Only client applications that explicitly enable the OCSP response check verification flags are affected.

FIPS impact: no

The FIPS modules in 4.0 and 3.6 are not affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

Patch / fix

  • OpenSSL OpenSSL 3.6.4, 4.0.2
  • openssl Debian 14 3.6.4-1

debian advisories DEBIAN-CVE-2026-54876

  • ruby3.3 hummingbird 1 3.3.10-23.5.hum1
  • ruby3.3-libs hummingbird 1 3.3.10-23.5.hum1
  • ruby3.3-bundled-gems hummingbird 1 3.3.10-23.5.hum1
  • ruby3.3-default-gems hummingbird 1 3.3.10-23.5.hum1
  • ruby3.4 hummingbird 1 3.4.10-31.6.hum1
  • ruby3.4-libs hummingbird 1 3.4.10-31.6.hum1
  • ruby3.4-bundled-gems hummingbird 1 3.4.10-31.6.hum1
  • ruby3.4-default-gems hummingbird 1 3.4.10-31.6.hum1

red hat advisories RHSA-2026:57986RHSA-2026:57994RHSA-2026:57021RHSA-2026:55543RHSA-2026:42825RHSA-2026:57565

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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-2026-54876 updated cvss 7.5

openssl: openssl-src: OpenSSL: Memory leak leads to Denial of Service in OCSP response checking

  • Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9
    affected: workaround, no fix available
  • Red Hat 3scale API Management Platform 2 3scale-amp2/system-rhel8
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/lightspeed-rhel9, ansible-automation-platform-27/lightspeed-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift Container Platform 4 kata-containers Red Hat OpenShift Container Platform 5 kata-containers Red Hat Trusted Profile Analyzer rhtpa/rhtpa-trustification-service-rhel9
    affected: workaround, no fix available
  • Red Hat Hardened Images chunkah 0.6.0-3.hum1, openssl 3.5.6-0.5.hum1, openssl3 3.5.7-2.2.hum1, ruby4.0 4.0.6-37.2.hum1, ruby3.3 3.3.10-23.5.hum1, ruby3.4 3.4.10-31.6.hum1, +18 more
    fixed: vendor fix RHSA-2026:42825
  • Red Hat Satellite 6.18 satellite/iop-vmaas-rhel9 1789611858
    fixed: vendor fix RHSA-2026:68764
  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-25/lightspeed-chatbot-rhel8 Red Hat Connectivity Link 1 rhcl-1/limitador-rhel9 Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9, rhdh/rhdh-must-gather-rhel9 Red Hat Enterprise Linux 6 openssl, openssl-perl
    +2 more products
    Red Hat Enterprise Linux 7 ovmf, OVMF, shim, AAVMF, firefox, mokutil, +6 more Red Hat Enterprise Linux 8 rls, edk2, rust, shim, cargo, clippy, +25 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 9 edk2, rust, shim, cargo, goose, clippy, +26 more
    not affected: component not present
show 2 more
  • Red Hat Enterprise Linux 10 edk2, igvm, rust, shim, goose, firefox, +6 more Red Hat Enterprise Linux AI (RHEL AI) 3 rust Red Hat Hardened Images rust, unbound, netavark, rust-podman-sequoia, rubygem3.3-rbs 3.4.0-23.5.hum1, rubygem3.3-rss 0.3.1-23.5.hum1, +49 more Red Hat JBoss Core Services jbcs-httpd24-openssl, jbcs-httpd24-openssl-libs, jbcs-httpd24-openssl-perl, jbcs-openssl-win6-x86_64.zip 3.5.5-SP4 Red Hat JBoss Web Server 6 jws-optional-native-components-win6-x86_64.zip 6.2.4.ER1 Red Hat OpenShift AI (RHOAI) rhoai/odh-llm-d-inference-scheduler-rhel9, rhoai/odh-model-registry-job-async-upload-rhel9
    +6 more products
    Red Hat OpenShift Container Platform 4 conmon-rs, openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 conmon-rs, openshift/ose-rhel-coreos-9 Red Hat OpenShift Update Service openshift-update-service/openshift-update-service-rhel8 Red Hat OpenStack Platform 16.2 rhosp-rhel8/openstack-keystone, rhosp-rhel8/openstack-nova-base, rhosp-rhel8/openstack-cinder-api, rhosp-rhel8/openstack-manila-api, rhosp-rhel8/openstack-ironic-base, rhosp-rhel8/openstack-nova-libvirt, +8 more Red Hat Quay 3 quay/quay-rhel9 Red Hat Satellite 6 puppet-agent, openvox-agent
    not affected: vulnerable code not present
  • Red Hat Trusted Profile Analyzer rhtpa/rhtpa-rhel10
    not affected: component 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
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-09).

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:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • OpenSSL OpenSSL

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime
Technology feeds

References

Sources

Fencer Intel 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.