Copyright © 2012 Red Hat, Inc. All rights reserved. Low 2026-08-25T00:00:00 openssl: excessive memory use buffering DTLS records for a future epoch 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CWE-405

Issue summary: Receiving a DTLS record for a future epoch while a handshake is in progress causes OpenSSL to buffer far more memory than the record itself requires. Impact summary: A peer can use a small amount of network traffic to make an OpenSSL DTLS endpoint retain a disproportionately large amount of memory, which may lead to a Denial of Service. CWE: CWE-405: Asymmetric Resource Consumption (Amplification) Description: While a DTLS handshake is in progress, a peer may legitimately have already moved on to the next epoch (for example, having sent its ChangeCipherSpec and Finished messages) before the local endpoint has processed the same transition, typically because of reordering on the underlying UDP transport. OpenSSL buffers such early records so that they can be processed once the local endpoint catches up. Buffering a record currently retains the entire read buffer it arrived in, which is sized to hold the largest possible DTLS record (around 16 kilobytes), rather than just the bytes that make up the record itself. Up to 100 such records may be buffered per connection. As a result, a peer that sends a stream of small forged records claiming to belong to the next epoch can cause an OpenSSL DTLS endpoint to retain around 1.7 megabytes of memory, despite sending only a small fraction of that amount of data over the network. An attacker therefore gains a memory amplification factor of around 1200, and can multiply the effect across as many associations as it is able to open, making this a remote memory exhaustion Denial of Service risk for DTLS servers. Since the memory retained per connection remains bounded, and any limit an application already places on the number of concurrent associations also bounds the total exposure, this issue has been assessed as Low severity. FIPS impact: no No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary. OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue. OpenSSL 4.0 users should upgrade to OpenSSL 4.0.2. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.4. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.8. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.7. OpenSSL 3.0 users should upgrade to OpenSSL 3.0.22. Premium support customers only: OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zi OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zr This issue was reported on 18 May 2026 by Amazon Web Services. The fix has been developed by Matt Caswell. -- cut (non-publishing metadata for internal use) -- Reported by: Amazon Web Services Fixed by: Matt Caswell

A flaw was found in OpenSSL. Receiving a DTLS (Datagram Transport Layer Security) record for a future epoch while a handshake is in progress causes OpenSSL to buffer an excessive amount of memory. This allows a peer to cause memory exhaustion, eventually resulting in a denial of service, using a small amount of network traffic.

To exploit this issue, an attacker needs to send a DTLS record for a future epoch while the handshake is in progress. This can cause excessive consumption of memory, eventually resulting in a denial of service. However, the retained memory is limited to 1.7MB per connection and the limit on simultaneous connections can prevent successful exploitation. For these reasons, this vulnerability has been rated with a low severity. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Red Hat Enterprise Linux 10 2026-09-14T00:00:00Z RHSA-2026:67154 openssl-1:3.5.8-1.el10_2 Red Hat Enterprise Linux 9 2026-09-14T00:00:00Z RHSA-2026:67165 openssl-1:3.5.8-1.el9_8 Red Hat Enterprise Linux 9 2026-09-14T00:00:00Z RHSA-2026:67165 openssl-1:3.5.8-1.el9_8 Red Hat Hardened Images 2026-08-25T00:00:00Z RHSA-2026:59635 openssl3-main-3.5.8-0.1.hum1 Red Hat Hardened Images 2026-08-25T00:00:00Z RHSA-2026:59641 openssl-main-3.5.8-0.1.hum1 Red Hat Update Infrastructure 5 2026-09-16T00:00:00Z RHSA-2026:67956 rhui5/cds-kubernetes-rhel9:1789479916 Red Hat Update Infrastructure 5 2026-09-16T00:00:00Z RHSA-2026:67956 rhui5/installer-rhel9:1789482961 Red Hat Developer Hub Fix deferred rhdh/rhdh-hub-rhel9 Red Hat Enterprise Linux 10 Fix deferred edk2 Red Hat Enterprise Linux 10 Fix deferred shim Red Hat Enterprise Linux 10 Fix deferred shim-unsigned-aarch64 Red Hat Enterprise Linux 10 Fix deferred shim-unsigned-x64 Red Hat Enterprise Linux 6 Fix deferred openssl Red Hat Enterprise Linux 7 Fix deferred openssl Red Hat Enterprise Linux 7 Fix deferred ovmf Red Hat Enterprise Linux 7 Fix deferred shim-signed Red Hat Enterprise Linux 8 Fix deferred compat-openssl10 Red Hat Enterprise Linux 8 Fix deferred edk2 Red Hat Enterprise Linux 8 Fix deferred mingw-openssl Red Hat Enterprise Linux 8 Fix deferred openssl Red Hat Enterprise Linux 8 Fix deferred shim Red Hat Enterprise Linux 8 Fix deferred shim-unsigned-aarch64 Red Hat Enterprise Linux 8 Fix deferred shim-unsigned-x64 Red Hat Enterprise Linux 9 Fix deferred compat-openssl11 Red Hat Enterprise Linux 9 Fix deferred edk2 Red Hat Enterprise Linux 9 Fix deferred shim Red Hat Enterprise Linux 9 Fix deferred shim-unsigned-aarch64 Red Hat Enterprise Linux 9 Fix deferred shim-unsigned-x64 Red Hat Hardened Images Not affected unbound Red Hat JBoss Core Services Fix deferred jbcs-httpd24-openssl Red Hat JBoss Core Services Fix deferred jbcs-openssl-win6-x86_64.zip Red Hat JBoss Web Server 6 Fix deferred jws-optional-native-components-win6-x86_64.zip Red Hat JBoss Web Server 7 Fix deferred jws-optional-native-components-win6-x86_64.zip Red Hat OpenShift Container Platform 4 Fix deferred openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 4 Fix deferred openshift/ose-rhel-coreos-9 Red Hat Satellite 6 Fix deferred openvox-agent Red Hat Satellite 6 Fix deferred puppet-agent Red Hat Satellite Client Fix deferred openvox-agent Red Hat Satellite Client Fix deferred puppet-agent https://www.cve.org/CVERecord?id=CVE-2026-54874 https://nvd.nist.gov/vuln/detail/CVE-2026-54874 https://openssl-library.org/news/secadv/20260825.txt