libexpat in Expat allows attackers to trigger large dynamic memory allocations via a small document that is submitted for parsing
CVE: CVE-2025-59375
Component: expat
CWE: CWE-770
Severity: Important
CVSS v3: 5.3/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Release date: 2025-09-15T00:00:00+00:00

A memory amplification vulnerability in libexpat allows attackers to trigger excessive dynamic memory allocations by submitting specially crafted XML input. A small input (~250 KiB) can cause the parser to allocate hundreds of megabytes, leading to denial-of-service (DoS) through memory exhaustion.

Statement: This issue is Important rather than Critical because, while it allows for significant resource exhaustion leading to denial-of-service (DoS), it does not enable arbitrary code execution, data leakage, or privilege escalation. The vulnerability stems from an uncontrolled memory amplification behavior in libexpat’s parser, where a relatively small XML payload can cause disproportionately large heap allocations. However, the flaw is limited in scope to service disruption and requires the attacker to submit a crafted XML document—something that can be mitigated with proper input validation and memory usage limits. Therefore, while the exploitability is high, the impact is confined to availability, not confidentiality or integrity, making it a high-severity but not critical flaw.

In Firefox and Thunderbird, where libexpat is a transitive userspace dependency, exploitation usually just crashes the application (app-level DoS), so it is classify as Moderate instead of Important.

Remediation:
For OpenShift Container Platform 4.12 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.12/html/release_notes

You may download the oc tool and use it to inspect release image metadata for the x86_64 architecture. The image digest may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

      The sha value for the release is as follows:

      (For x86_64 architecture)
      The image digest is sha256:9ea794d2dd24ff7377534edfb0447e5398a28919a84300cc79fe7bb8ae550d1b

All OpenShift Container Platform 4.12 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.12/html-single/updating_clusters/index#updating-cluster-within-minor.
Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258
For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.13/html/release_notes

You may download the oc tool and use it to inspect release image metadata for x86_64 architecture. The image digest may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

      The sha value for the release is as follows:

      (For x86_64 architecture)
      The image digest is sha256:b373f9055bf22079e7baf0c7b3ea21067248932bb0ec57fa0af30c51810bbe91

All OpenShift Container Platform 4.13 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.13/html-single/updating_clusters/index#updating-cluster-within-minor.
For OpenShift Container Platform 4.14 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:9e91245847127c920394c66c06a2c5485a1e5e54c8254326f18c04fee139fb43

      (For s390x architecture)
      The image digest is sha256:cf49729558f112fb860b847d6a036b5545ecbf3d7ecce1107081251373be848e

      (For ppc64le architecture)
      The image digest is sha256:4bf0c14c8511361620a3d6c098f087ae6f4be7b4972314cadbabb3945f43b517

      (For aarch64 architecture)
      The image digest is sha256:279e8a5c8c3954f85de55780ac18e84cc21e052836131e921f1305094b1b4029

All OpenShift Container Platform 4.14 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.15 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html/release_notes/

You may download the oc tool and use it to inspect release image metadata
for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests
may be found at
https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:d517885ee59d46c2aca8be69fdcf916f78a510ae76a5a9f7875c1c5ab3cfc3c1

      (For s390x architecture)
      The image digest is sha256:3a4a7c87e8ca5f4e3803f8f203599b25055276a532df8e0b66ec4ec2ebc51f4c

      (For ppc64le architecture)
      The image digest is sha256:f34818181660a9f58a59e06dbe58f24de82dcbb688e5f940a41e62e08f1edf94

      (For aarch64 architecture)
      The image digest is sha256:24eeb2ea15ac709ed08df9b6f1a5d1ac334c4f7335c0ae5249e17298ab297517

All OpenShift Container Platform 4.15 users are advised to upgrade to these
updated packages and images when they are available in the appropriate
release channel. To check for available updates, use the OpenShift CLI (oc)
or web console. Instructions for upgrading a cluster are available at
https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:283a4968c61885c67fd17ea4d6920b665c98d53fa85fc897e067d3c4c131da3b

      (For s390x architecture)
      The image digest is sha256:5db06d746a26930aa3a8ec756f77cfcf76bcfb838327a5c71d3a0e6d920b85c6

      (For ppc64le architecture)
      The image digest is sha256:444378df90349f12c84ec1447dfb2afa40fd28e6596d8d9ab9a37b9013fc6a62

      (For aarch64 architecture)
      The image digest is sha256:c837b6a0325105e8f1487cdebf12d1b41eaa609a88f37baf986f5361ba66b08b

All OpenShift Container Platform 4.16 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.17 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.17/html/release_notes/

You may download the oc tool and use it to inspect release image metadata
for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests
may be found at
https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:d49a4f1a4532e3822e8769a97d87f538f9101701d3997e6e883c8abff7b58a43

      (For s390x architecture)
      The image digest is sha256:baded7c05358eda3d7bc20efdc3d2b963ba80f1639c2c80b2c58bc216a1375d1

      (For ppc64le architecture)
      The image digest is sha256:4714f7f59793e8f77cc5a95eb918bd43f9a6ff31de1b35fb59b45a07f7a3f118

      (For aarch64 architecture)
      The image digest is sha256:73e2429c13a91ea4e5031c61f94c57884a7251ece3e1bbb338523e7bf8246903

All OpenShift Container Platform 4.17 users are advised to upgrade to these
updated packages and images when they are available in the appropriate
release channel. To check for available updates, use the OpenShift CLI (oc)
or web console. Instructions for upgrading a cluster are available at
https://docs.redhat.com/en/documentation/openshift_container_platform/4.17/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.18 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/release_notes/

You may download the oc tool and use it to inspect release image metadata
for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests
may be found at
https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:64e8c4cbd3199beb1ebb8d6a208cb81fdfe62f4e52d7586033f534d35f981244

      (For s390x architecture)
      The image digest is sha256:5b964fa43873a20a66b95769bbcd6c31b028f505281fb045bb3c2ed6ca114e91

      (For ppc64le architecture)
      The image digest is sha256:2108325c5ee08249e1b0c0ad6a3daab197f5e2a1a83c8600d27c49ad0ff94307

      (For aarch64 architecture)
      The image digest is sha256:b465cef295a81eaf055c87a9af6d8ecdcc11cb1e898895d6df527eb155a7ff82

All OpenShift Container Platform 4.18 users are advised to upgrade to these
updated packages and images when they are available in the appropriate
release channel. To check for available updates, use the OpenShift CLI (oc)
or web console. Instructions for upgrading a cluster are available at
https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.19 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this  synchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:e4377ba202c97eccba15c3a428cd4e532a02d5420d5b8918cdd3284404abb1ba

      (For s390x architecture)
      The image digest is sha256:0a15e17381e77d0afdf331ae3c455e091ffd454cf69966f041abf28ad7494be9

      (For ppc64le architecture)
      The image digest is sha256:b7ec15e179936b7c832c59ee3e68c70151d16e5cb9270d1bd0f7fb6dd78e438c

      (For aarch64 architecture)
      The image digest is sha256:87fd3d95d4b0f67500c624b64a1bf69873a8ef361612fed314066f01b78677ec

All OpenShift Container Platform 4.19 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.20 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:2d228e6d0b5a5ef2d7eb40bc171ad44f06b990d7adb678914e5d9d047e72568d

      (For s390x architecture)
      The image digest is sha256:af6307b4034d762e4b50edfcbeff0bdd58d4530cecb960ad777fe977c5775d11

      (For ppc64le architecture)
      The image digest is sha256:7ce9923ffac52e14a5674744810689466a49479ace1525d96e1c81c6f4928eaf

      (For aarch64 architecture)
      The image digest is sha256:a1b224a91987e73d8e27b920b118fa13897c45d832fbdf38ec72d50d0e6cb8dc

All OpenShift Container Platform 4.20 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at
https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html-single/updating_clusters/index#updating-cluster-cli.
For more information visit https://access.redhat.com/errata/RHSA-2025:23080
For more information visit https://access.redhat.com/errata/RHSA-2025:23202
For more information visit https://access.redhat.com/errata/RHSA-2025:23204
For more information visit https://access.redhat.com/errata/RHSA-2025:23078
For more information visit https://access.redhat.com/errata/RHSA-2026:3461
For more information visit https://access.redhat.com/errata/RHSA-2026:3462
For more information visit https://access.redhat.com/errata/RHSA-2025:23079
For more information visit https://access.redhat.com/errata/RHSA-2025:23449
For more information visit https://access.redhat.com/errata/RHSA-2025:23205
For more information visit https://access.redhat.com/errata/RHSA-2025:23209
If you are using an earlier version of RHACS, you are advised to
upgrade to the version of RHACS mentioned in the synopsis and release
notes in order to take advantage of the enhancements, bug fixes, and/or
security patches in the release.
If you are using an earlier version of RHACS, you are advised to
upgrade to the version of RHACS mentioned in the synopsis and release
notes in order to take advantage of the enhancements, bug fixes, and/or
security patches in the release.
The container images provided by this update can be downloaded from the
Red Hat container registry at registry.redhat.io using the "podman pull" command.
The container images provided by this update can be downloaded from the
Red Hat container registry at registry.redhat.io using the "podman pull" command.
The containers required to run Discovery can be installed through discovery-installer
RPM. See the official documentation for more details.
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

The References section of this erratum contains a download link. You must be logged in to download the update.
For details on how to apply this update, refer to:

https://docs.redhat.com/en/documentation/openshift_container_platform/latest/html/operators/administrator-tasks#olm-upgrading-operators
Before applying this update, make sure all previously released errata relevant
to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258
The container images provided by this release, apart from the installer, should be deployed using rhui-installer utility.
See the official documentation for more details.
To mitigate the issue, limit XML input size and complexity before parsing, and avoid accepting compressed or deeply nested XML. Use OS-level resource controls (like ulimit or setrlimit()) to cap memory usage, or run the parser in a sandboxed or isolated process with strict memory and CPU limits. This helps prevent denial-of-service by containing excessive resource consumption.