--- id: CVE-2026-54876 title: |- 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… 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… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-401 - CWE-772 published: '2026-08-05' updated: '2026-08-28' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-54876' references: - url: >- https://github.com/openssl/openssl/commit/155b5fe0f93365e6df1c56ee3606b121080c6c12 label: openssl-security@openssl.org - url: >- https://github.com/openssl/openssl/commit/d8c51048ac037a21bae0f41cad7a3920dc7f3638 label: openssl-security@openssl.org - url: 'https://openssl-library.org/news/secadv/20260805.txt' label: openssl-security@openssl.org - url: 'http://www.openwall.com/lists/oss-security/2026/08/05/8' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54876.json - url: 'https://access.redhat.com/security/cve/CVE-2026-54876' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2511600' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-54876' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-54876' - url: 'https://access.redhat.com/errata/RHSA-2026:42825' - url: 'https://access.redhat.com/errata/RHSA-2026:56097' - url: 'https://access.redhat.com/errata/RHSA-2026:57021' - url: 'https://access.redhat.com/errata/RHSA-2026:55543' - url: 'https://access.redhat.com/errata/RHSA-2026:57986' - url: 'https://access.redhat.com/errata/RHSA-2026:57994' - url: 'https://access.redhat.com/errata/RHSA-2026:57565' - url: 'https://access.redhat.com/errata/RHSA-2026:68764' tags: - nvd - csaf - vex - red-hat - score-dispute epss: 0.00261 epssPercentile: 0.18192 ingestedAt: '2026-08-29T16:39:13.787Z' vendor: Red Hat product: Red Hat Enterprise Linux 10 affected: - confidential_cluster_operator - 3scale_api_management_platform 2 - ansible_automation_platform 2 - connectivity_link 1 - openstack_platform 16.2 - quay 3 - satellite 6 - confidential_compute_attestation - lightspeed_core - logging_subsystem_for_red_hat_openshift - migration_toolkit_for_applications 8 - openshift_lightspeed - openshift_service_mesh 3 - pen_drive_powered_by_red_hat_lightspeed - advanced_cluster_security 4 - ansible_automation_platform_ansible_core 2 - developer_hub - directory_server 13 - discovery 2 - enterprise_linux 10 - enterprise_linux 6 - enterprise_linux 7 - enterprise_linux 8 - enterprise_linux 9 - enterprise_linux_command_line_assistant - jboss_web_server 7 - offline_knowledge_portal - openshift_ai_rhoai - openshift_container_platform 4 - openshift_update_service - trusted_artifact_signer - trusted_profile_analyzer - hardened_images patched: - hardened_images scores: nvd: 7.5 vendor: 3.7 --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:42825** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:42825) - **RHSA-2026:56097** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-18 · [advisory](https://access.redhat.com/errata/RHSA-2026:56097) - **RHSA-2026:57021** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:57021) - **RHSA-2026:55543** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:55543) - **RHSA-2026:57986** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:57986) - **RHSA-2026:57994** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:57994) - **RHSA-2026:57565** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:57565) - **Red Hat VEX** · Low · affected: Confidential Cluster Operator, Red Hat 3scale API Management Platform 2, Red Hat Ansible Automation Platform 2, Red Hat Connectivity Link 1, Red Hat OpenStack Platform 16.2, Red Hat Quay 3, … · no fix planned: Red Hat 3scale API Management Platform 2, Red Hat Ansible Automation Platform 2, Red Hat Connectivity Link 1, Confidential Cluster Operator, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54876.json) - **RHSA-2026:68764** · Red Hat · fixed in: Red Hat Satellite 6.18 · released 2026-09-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:68764)