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Fencer Vulns
high 7.5

CVE-2026-119194 json

pyasn1: Quadratic CPU use in schemaless BER/CER/DER container decoding

published 2026-10-29 10 d ago modified 2026-11-03 5 d ago also GHSA-fm9c-5rcf-2q5p , EUVD-2026-113350

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

pyasn1 is a generic ASN.1 library for Python. From 0.3.3 until 0.6.5, schemaless container decoding stores every decoded component's TagSet in a growing set even though only one-versus-multiple tag types must be distinguished. Attacker-controlled BER, CER, or DER input contains many distinct long tag IDs whose TagSet hashes collide. Each later set insertion compares against an increasing number of earlier colliding tags in ConstructedPayloadDecoderBase._decodeComponentsSchemaless, producing quadratic CPU work while decoded values and order remain valid. Repeated inputs can exhaust decoder CPU and reduce service availability. This issue is fixed in version 0.6.5.

Patch / fix

  • pypi pyasn1 0.6.5
  • pyasn1 Debian 14 0.6.5-1

debian advisories DEBIAN-CVE-2026-119194

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-2026-119194 updated cvss 7.5

pyasn1: pyasn1: Denial of Service via hash collisions in schemaless decoding

  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-backend-rhel9 Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9 Red Hat Fence Agents Remediation Operator workload-availability/fence-agents-remediation-rhel9-operator 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
    +1 more products
    Red Hat Migration Toolkit for Virtualization migration-toolkit-virtualization/mtv-rhel9-operator
    affected: no fix available
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-service-api-rhel9, openshift-lightspeed/lightspeed-agentic-sandbox-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaii/vllm-rocm-rhel9, rhaii-fast/vllm-tpu-rhel9, rhaii-fast/vllm-rocm-rhel9
    affected: no fix available
  • Red Hat Ansible Automation Platform 2 python3x-pyasn1 0.4.8-1.el8ap, python3.11-pyasn1 0.5.1-1.el9ap, python3.12-pyasn1 0.6.4-1.el9ap, automation-controller 4.7.18-1.el9ap, ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, +48 more
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 7 resource-agents, resource-agents-gcp, resource-agents-sap, sap-cluster-connector, resource-agents-aliyun, resource-agents-sap-hana, +1 more Red Hat Enterprise Linux 8 fence-agents, python3-pyasn1, resource-agents, fence-agents-all, fence-agents-apc, fence-agents-aws, +50 more Red Hat Enterprise Linux 9 fence-virt, fence-virtd, fence-agents, python3-pyasn1, fence-virtd-cpg, fence-virtd-tcp, +54 more Red Hat Enterprise Linux 10 python-pyasn1 0.6.4-1.el10 Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-rocm-rhel9, rhelai3/bootc-azure-rocm-rhel9 Red Hat OpenShift AI (RHOAI) rhoai/odh-automl-rhel9, rhoai/odh-mlflow-rhel9, rhoai/odh-autorag-rhel9, rhoai/odh-ogx-core-rhel9, rhoai/odh-feature-server-rhel9, rhoai/odh-llama-stack-core-rhel9, +29 more
    +7 more products
    Red Hat OpenShift Container Platform 4 python-pyasn1 0.6.4-1.el10, openshift4/ose-ansible-rhel9-operator Red Hat OpenShift Container Platform 5 python-pyasn1 0.6.4-1.el10, openshift5/ose-ansible-rhel9-operator Red Hat OpenStack Platform 16.2 python3-pyasn1, python3-pyasn1-modules, python-pyasn1 0.6.4-1.el10 Red Hat OpenStack Platform 17.1 python-pyasn1 0.6.4-1.el10 Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Satellite 6 satellite/iop-advisor-backend-rhel9 Red Hat Trusted Artifact Signer rhtas/rh-sigstore-a2a-rhel9
    affected: no fix available
  • Red Hat Trusted Artifact Signer 1.5 rhtas/model-transparency-rhel9 1793696578
    fixed: vendor fix RHSA-2026:95261
  • Red Hat OpenShift Service Mesh 3 openshift-service-mesh/kiali-rhel9-operator
    not affected: vulnerable code not in execute path
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/volsync-rhel9, rhacm2/volsync-operator-bundle
    not affected: vulnerable code not present
show 2 more
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-kserve-controller-rhel9
    not affected: component not present
  • Red Hat Service Telemetry Framework 1.5 stf/smart-gateway-rhel9-operator, stf/prometheus-webhook-snmp-rhel9, stf/service-telemetry-rhel9-operator
    not affected: vulnerable code not in execute path

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
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 d ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/pyasn1/pyasn1/security/advisories/GHSA-fm9c-5rcf-2q5p referenced PoC, tagged "exploit" by a source, unverified

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

Affected packages

ecosystem package affected fixed in
pypi pyasn1
>=0.3.3, <0.6.5
0.6.5

Affected products

  • pyasn1 pyasn1

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

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.