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Fencer Vulns
high 7.5

CVE-2026-59884 json

pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs

published 2026-07-14 3 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-43956 , GHSA-m4p7-r5rc-7g4j , PYSEC-2026-3455

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.

Patch / fix

  • pypi pyasn1 0.6.4
  • pyasn1 pyasn1 0.6.4
  • pyasn1 Debian 12 0.4.8-3+deb12u3
  • pyasn1 Debian 13 0.6.1-1+deb13u3
  • pyasn1 Debian 14 0.6.4-1

debian advisories DEBIAN-CVE-2026-59884

  • pyasn1 Ubuntu 22.04 LTS 0.4.8-1ubuntu0.3
  • pyasn1 Ubuntu 24.04 LTS 0.4.8-4ubuntu0.3
  • pyasn1 Ubuntu 26.04 LTS 0.6.3-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-59884

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jaeger hummingbird 1 2.19.0-1.1.hum1

red hat advisories RHSA-2026:40236

  • python-pyasn1 Linux Micro 6.1 0.5.0-slfo.1.1_4.1
  • python-pyasn1 Linux Micro 6.0 0.5.0-5.1
  • python-pyasn1 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 0.5.0-150400.12.16.1
  • python-pyasn1 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 0.6.1-160000.5.1

suse advisories SUSE-SU-2026:23167-1SUSE-SU-2026:23006-1SUSE-SU-2026:3238-1SUSE-SU-2026:22765-1SUSE-SU-2026:22830-1

  • python-pyasn1 openSUSE Leap 16.0 0.6.1-160000.5.1
  • python-pyasn1 openSUSE Tumbleweed 0.6.4-1.1

opensuse advisories openSUSE-SU-2026:21392-1openSUSE-SU-2026:11318-1

  • python-pyasn1 Azure Linux 3.0 0.4.8-3

azure linux advisories AZL-92433

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-2026-59884 updated cvss 5.9

python-pyasn1: pyasn1: Denial of Service via crafted BER input

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/vulnerability-analysis-rhel9 Red Hat Lightspeed Core lightspeed-core/lightspeed-stack-rhel9 Red Hat Migration Toolkit for Applications 8 mta/mta-rhel9-operator, mta/mta-solution-server-rhel9 Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-rhel8-operator Red Hat Migration Toolkit for Virtualization mtv-candidate/mtv-rhel9-operator, migration-toolkit-virtualization/mtv-rhel9-operator Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-service-api-rhel9, openshift-lightspeed/lightspeed-agentic-sandbox-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9
    +2 more products
    Red Hat OpenShift Service Mesh 3 openshift-service-mesh/kiali-rhel9-operator Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/volsync-rhel9, rhacm2/volsync-operator-bundle
    affected: workaround, no fix available “Fix deferred”
  • Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaiis/vllm-rocm-rhel9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-27/gateway-rhel9, ansible-automation-platform-24/ee-minimal-rhel8, ansible-automation-platform-24/ee-minimal-rhel9, +32 more Red Hat Ceph Storage 7 rhceph/rhceph-7-rhel9 Red Hat Ceph Storage 8 rhceph/rhceph-8-rhel9 Red Hat Ceph Storage 9 rhceph/rhceph-9-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 python-pyasn1 0.6.2-1.el10_1
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 python2-pyasn1, resource-agents, resource-agents-gcp, resource-agents-sap, sap-cluster-connector, python2-pyasn1-modules, +4 more Red Hat Enterprise Linux 8 python3-pyasn1, python3-pyasn1-modules, python-pyasn1 0.6.2-1.el10_1 Red Hat Enterprise Linux 9 python3-pyasn1, python3-pyasn1-modules, rhel9/keylime-verifier, rhel9/keylime-registrar, python-pyasn1 0.6.2-1.el10_1 Red Hat Enterprise Linux 10 rhel10/keylime-verifier, rhel10/keylime-registrar, python-pyasn1 0.6.2-1.el10_1
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-rocm-rhel9, rhelai3/bootc-azure-rocm-rhel9 Red Hat OpenShift AI (RHOAI) rhoai/odh-pipelines-components-rhel9, rhoai/odh-ml-pipelines-runtime-generic-rhel9, rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Container Platform 4 python-pyasn1 0.6.2-1.el10_1, openshift4/ose-ansible-rhel9-operator Red Hat OpenShift Container Platform 5 python-pyasn1 0.6.2-1.el10_1, openshift5/ose-ansible-rhel9-operator Red Hat OpenStack Platform 16.2 python3-pyasn1, python3-pyasn1-modules, python-pyasn1 0.6.2-1.el10_1 Red Hat OpenStack Platform 17.1 python-pyasn1 0.6.2-1.el10_1 Red Hat OpenStack Platform 18.0 rhoso-operators/ee-openstack-ansible-ee-rhel9 Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9
    +3 more products
    Red Hat Satellite 6 python-pyasn1 0.6.2-1.el10_1, satellite/iop-advisor-engine-rhel9, satellite/iop-advisor-backend-rhel9 Red Hat Trusted Artifact Signer rhtas/segment-reporting-rhel9, rhtas/model-transparency-rhel9 Red Hat Service Telemetry Framework 1.5 stf/smart-gateway-rhel9-operator, stf/prometheus-webhook-snmp-rhel9, stf/service-telemetry-rhel9-operator
    affected: workaround, no fix available “Fix deferred”
  • Red Hat AI Inference Server 3.3 rhaiis/model-opt-cuda-rhel9 1787601159
    fixed: vendor fix RHSA-2026:59518
show 7 more
  • Red Hat AI Inference Server 3.4 rhaii/vllm-rocm-rhel9 1791856725
    fixed: vendor fix RHSA-2026:83121
  • Red Hat Enterprise Linux AI 3.3 rhelai3/bootc-cuda-rhel9 1788260684, rhelai3/bootc-aws-cuda-rhel9 1788273908, rhelai3/bootc-gcp-cuda-rhel9 1788273977, rhelai3/disk-image-cuda-rhel9 1788290314, rhelai3/bootc-azure-cuda-rhel9 1788273909
    fixed: vendor fix RHSA-2026:62336
  • Red Hat Hardened Images jaeger 2.19.0-1.1.hum1
    fixed: vendor fix RHSA-2026:40236
  • Red Hat OpenShift AI 2.25 rhoai/odh-feature-server-rhel9 1792148523
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.3 rhoai/odh-mlflow-rhel9 1789653606, rhoai/odh-llama-stack-core-rhel9 1789121286
    fixed: vendor fix RHSA-2026:73987
  • Red Hat OpenShift AI 3.4 rhoai/odh-mlflow-rhel9 1787226790, rhoai/odh-feature-server-rhel9 1791863220, rhoai/odh-llama-stack-core-rhel9 1790958470, rhoai/odh-th06-cpu-torch210-py312-rhel9 1787076778, rhoai/odh-th06-rocm64-torch291-py312-rhel9 1787076481, rhoai/odh-th06-cuda130-torch210-py312-rhel9 1787077779, +16 more
    fixed: vendor fix RHSA-2026:84734
  • Red Hat Enterprise Linux AI 3.3 rhelai3/bootc-rocm-rhel9 1788260620, rhelai3/bootc-azure-rocm-rhel9 1788273908 Red Hat Hardened Images mariadb11.8 11.8.8-3.hum1, python-trustme 1.2.1-2.hum1 Red Hat OpenShift AI (RHOAI) rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-kserve-controller-rhel9, rhoai/odh-kserve-storage-initializer-rhel9, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1791853525, rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-operator-bundle 1792571069, rhoai/odh-vllm-cuda-rhel9 1791358976, +65 more
    not affected: vulnerable code not present

2 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 SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 49% 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
GitHub 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

Affected packages

ecosystem package affected fixed in
pypi pyasn1
<0.6.4
0.6.4

Affected products

  • pyasn1 pyasn1

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.