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Fencer Vulns
high 7.5

CVE-2023-33953 json

Denial-of-Service in gRPC

published 2023-08-09 3 y ago modified 2026-07-07 4 mo ago also GHSA-496j-2rq6-j6cc , PYSEC-2026-1424 , EUVD-2023-2204

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 41%
public exploits
0
none known

Summary

gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks:

- Unbounded memory buffering in the HPACK parser - Unbounded CPU consumption in the HPACK parser

The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client.

The unbounded memory buffering bugs:

- The header size limit check was behind the string reading code, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb. - HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse. - gRPC’s metadata overflow check was performed per frame, so that the following sequence of frames could cause infinite buffering: HEADERS: containing a: 1 CONTINUATION: containing a: 2 CONTINUATION: containing a: 3 etc…

Patch / fix

  • pypi grpcio 1.53.2, 1.54.3, 1.55.2, 1.56.2
  • rubygems grpc 1.53.2, 1.54.3, 1.55.2, 1.56.2
  • Google gRPC 1.56.1
  • grpc grpc 1.53.2, 1.55.2, 1.56.2, 154.3
  • rhc-worker-playbook RHEL 9 0.1.10-1.el9_5

red hat advisories RHSA-2024:10761

  • grpc SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +12 more 1.25.0-150200.3.10.1
  • re2 SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Module for Public Cloud 15 SP5 +5 more 20240201-150400.9.3.1
  • grpc SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Module for Public Cloud 15 SP5 +6 more 1.60.0-150400.8.3.2
  • protobuf SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Module for Python 3 15 SP5 +16 more 25.1-150400.9.3.1
  • abseil-cpp SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Workstation Extension 15 SP5 +13 more 20230802.1-150400.10.4.1
  • python-abseil SLE Module for Python 3 15 SP5, openSUSE Leap 15.5 1.4.0-150400.9.3.1
  • python-grpcio SLE Module for Python 3 15 SP5, openSUSE Leap 15.5 1.60.0-150400.9.3.2
  • opencensus-proto openSUSE Leap 15.5 0.3.0+git.20200721-150400.9.3.1

suse advisories SUSE-SU-2026:0840-1SUSE-SU-2024:0573-1

  • grpc Azure Linux 3.0 1.62.0-2
  • python-tensorboard CBL-Mariner 2.0 2.11.0-2

azure linux advisories AZL-34770AZL-39394

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-2023-33953 updated cvss 7.5

gRPC: hpack table accounting errors can lead to denial of service

  • Red Hat Enterprise Linux AppStream (v. 9) rhc-worker-playbook 0.1.10-1.el9_5
    fixed: vendor fix RHSA-2024:10761
  • Red Hat Builds for Red Hat OpenShift openshift-builds-waiters-rhel9, openshift-builds-webhook-rhel9, openshift-builds-rhel9-operator, openshift-builds-controller-rhel9, openshift-builds-git-cloner-rhel9, openshift-builds-triggers-container, +12 more Red Hat cert-manager Operator for Red Hat OpenShift cert-manager/cert-manager-operator-rhel9, cert-manager/jetstack-cert-manager-rhel9, cert-manager/jetstack-cert-manager-acmesolver-rhel9 Red Hat Cryostat 3 cryostat-tech-preview/cryostat-storage-rhel8, cryostat-tech-preview/cryostat-ose-oauth-proxy-rhel8 Red Hat Custom Metric Autoscaler operator for Red Hat Openshift custom-metrics-autoscaler/custom-metrics-autoscaler-rhel8, custom-metrics-autoscaler-tech-preview/custom-metrics-autoscaler-adapter-rhel8, custom-metrics-autoscaler-tech-preview/custom-metrics-autoscaler-rhel8-operator Red Hat Kube Descheduler Operator kube-descheduler-operator/descheduler-rhel9, kube-descheduler-operator/kube-descheduler-rhel9-operator Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/logging-loki-rhel8, openshift-logging/loki-rhel8-operator, openshift-logging/lokistack-gateway-rhel8
    +33 more products
    Red Hat Logical Volume Manager Storage lvms4/topolvm-rhel9, lvms4/lvms-rhel9-operator, lvms4/lvms-must-gather-rhel9 Red Hat Migration Toolkit for Applications 7 mta/mta-cli-rhel9, mta/mta-analyzer-addon-rhel9, mta-java-external-provider-container, mta-dotnet-external-provider-container, mta-generic-external-provider-container Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-registry-rhel8, rhmtc/openshift-migration-controller-rhel8, rhmtc/openshift-migration-velero-plugin-for-mtc-rhel8 Red Hat Migration Toolkit for Virtualization migration-toolkit-virtualization/mtv-validation-rhel9 Red Hat Multiarch Tuning Operator multiarch-tuning-rhel9-operator Red Hat Multicluster Engine for Kubernetes multicluster-engine/hive-rhel8, multicluster-engine/work-rhel8, multicluster-engine/placement-rhel8, multicluster-engine/cluster-api-rhel9, multicluster-engine/registration-rhel8, multicluster-engine/addon-manager-rhel9, +11 more Red Hat Network Observability Operator network-observability/network-observability-ebpf-agent-rhel9, network-observability/network-observability-flowlogs-pipeline-rhel9 Red Hat OpenShift API for Data Protection oadp/oadp-velero-rhel9, oadp/oadp-rhel8-operator, oadp/oadp-mustgather-rhel8, oadp/oadp-velero-plugin-rhel8, oadp/oadp-velero-plugin-for-aws-rhel8, oadp/oadp-velero-plugin-for-gcp-rhel9, +3 more Red Hat OpenShift Developer Tools and Services ocp-tools-4/jenkins-rhel8, ocp-tools-4/jenkins-agent-base-rhel8 Red Hat OpenShift Run Once Duration Override Operator run-once-duration-override-operator/run-once-duration-override-rhel8, run-once-duration-override-operator/run-once-duration-override-rhel9-operator Red Hat OpenShift Secondary Scheduler Operator openshift-secondary-scheduler-operator/secondary-scheduler-rhel9-operator Red Hat OpenShift Serverless openshift-serverless-clients, openshift-serverless-1/client-kn-rhel8, openshift-serverless-1/serving-queue-rhel8, openshift-serverless-1/eventing-mtping-rhel8, openshift-serverless-1/kourier-control-rhel8, openshift-serverless-1/serving-webhook-rhel8, +25 more Red Hat OpenShift Service Mesh 2 openshift-service-mesh/kiali-rhel8, openshift-service-mesh/pilot-rhel8, openshift-service-mesh/proxyv2-rhel9, openshift-service-mesh/istio-cni-rhel8, openshift-service-mesh/ratelimit-rhel8, openshift-service-mesh/istio-rhel8-operator Red Hat OpenShift Source-to-Image (S2I) source-to-image-container Red Hat Advanced Cluster Management for Kubernetes 2 volsync-container, rhacm2/subctl-rhel9, rhacm2/thanos-rhel7, rhacm2/prometheus-rhel8, rhacm2/acm-grafana-rhel8, rhacm2/observatorium-rhel8, +16 more Red Hat Advanced Cluster Security 4 advanced-cluster-security/rhacs-main-rhel8, advanced-cluster-security/rhacs-roxctl-rhel8, advanced-cluster-security/rhacs-scanner-rhel8, advanced-cluster-security/rhacs-rhel8-operator, advanced-cluster-security/rhacs-central-db-rhel8, advanced-cluster-security/rhacs-scanner-db-rhel8, +4 more Red Hat Ceph Storage 5 rhceph/rhceph-5-dashboard-rhel8 Red Hat Ceph Storage 6 rhceph/rhceph-promtail-rhel9, rhceph/rhceph-6-dashboard-rhel9 Red Hat Ceph Storage 7 rhceph/grafana-rhel9, rhceph/rhceph-promtail-rhel9 Red Hat Connectivity Link 1 rhcl-1/authorino-container, rhcl-1/dns-operator-container, rhcl-1/rhcl-operator-container, rhcl-1/dns-operator-bundle-container, rhcl-1/rhcl-operator-bundle-container Red Hat Developer Hub 1 controller-rhel9-operator Red Hat Enterprise Linux 8 podman, skopeo, buildah, podman-tests, skopeo-tests, buildah-tests, +12 more Red Hat Enterprise Linux 9 podman, skopeo, buildah, grafana, ignition, grafana-pcp, +18 more Red Hat Enterprise Linux 10 podman, skopeo, buildah, grafana, ignition, grafana-pcp, +1 more Red Hat OpenShift AI (RHOAI) odh-operator-container, odh-mm-rest-proxy-container, odh-kueue-controller-container, odh-model-controller-container, odh-ml-pipelines-cache-container, odh-ml-pipelines-driver-container, +13 more Red Hat OpenShift Cluster Manager CLI ocm-cli-rhel9 Red Hat OpenShift Container Platform 3.11 apb, podman, cri-tools, csi-attacher, csi-provisioner, atomic-openshift, +24 more Red Hat OpenShift Container Platform 4 grpc, podman, skopeo, grpc-cli, grpc-plugins, podman-tests, +59 more Red Hat OpenShift Container Platform Assisted Installer 1 appliance Red Hat Openshift Container Storage 4 mcg, ocs4/cephcsi-rhel8, ocs4/mcg-rhel8-operator, ocs4/ocs-rhel8-operator, ocs4/ocs-must-gather-rhel8, ocs4/rook-ceph-rhel8-operator, +1 more Red Hat Openshift Data Foundation 4 odf4/odf-cli-rhel9, odf4/mcg-rhel9-operator, odf4/ocs-rhel9-operator, odf4/odr-rhel8-operator, ceph-cosi-driver-container, odf4/odf-cosi-sidecar-rhel9, +1 more Red Hat OpenShift Data Science (RHODS) rhods/odh-rhel8-operator, rhods/odh-mm-rest-proxy-rhel8, odh-kueue-controller-container, rhods/odh-model-controller-rhel8, rhods/odh-codeflare-operator-rhel8, rhods/odh-ml-pipelines-cache-rhel8, +7 more Red Hat OpenShift Dev Spaces devspaces/udi-rhel8, devspaces/traefik-rhel8, devspaces/imagepuller-rhel8, devspaces/devspaces-rhel8-operator
    not affected: vulnerable code not present

11 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 ICSA-24-137-07 updated cvss 7.5

Siemens SIMATIC RTLS Locating Manager

  • Siemens SIMATIC RTLS Locating Manager (6GT2780-0DA00) <V3.0.1.1 Siemens SIMATIC RTLS Locating Manager (6GT2780-0DA10) <V3.0.1.1 Siemens SIMATIC RTLS Locating Manager (6GT2780-0DA20) <V3.0.1.1 Siemens SIMATIC RTLS Locating Manager (6GT2780-0DA30) <V3.0.1.1 Siemens SIMATIC RTLS Locating Manager (6GT2780-1EA10) <V3.0.1.1 Siemens SIMATIC RTLS Locating Manager (6GT2780-1EA20) <V3.0.1.1
    +1 more products
    Siemens SIMATIC RTLS Locating Manager (6GT2780-1EA30) <V3.0.1.1
    affected: fixed in V3.0.1.1, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi grpcio
<1.53.2
>=1.54.0, <1.54.3
>=1.55.0, <1.55.2
>=1.56.0, <1.56.2
1.53.2
1.54.3
1.55.2
1.56.2
rubygems grpc
<1.53.2
>=1.54.0, <1.54.3
>=1.55.0, <1.55.2
>=1.56.0, <1.56.2
1.53.2
1.54.3
1.55.2
1.56.2

Affected products

  • Google gRPC
  • grpc grpc

Classification

Weakness
  • CWE-834 Excessive Iteration
  • CWE-789 Memory Allocation with Excessive Size Value
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.