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Fencer Vulns
high 7.5

CVE-2026-119195 json

pyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decoding

published 2026-10-29 10 d ago modified 2026-10-30 9 d ago also GHSA-9m75-vc3g-4x39 , EUVD-2026-113351

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 44%
public exploits
0
none known

Summary

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, constructed string and indefinite-length ANY decoding repeatedly concatenates each fragment onto a growing bytes value. Attacker-controlled BER or CER data can use many constructed OCTET STRING or character-string fragments. DER rejects constructed OCTET STRING without a schema, but accepts its definite-length form when asn1Spec selects univ.OctetString; it also accepts constructed character strings such as UTF8String without a schema, even though those encodings are not valid DER. The separate indefinite-length ANY path is reachable in BER and CER when asn1Spec selects univ.Any; DER rejects indefinite lengths. OctetStringPayloadDecoder uses growing header concatenation and AnyPayloadDecoder.indefLenValueDecoder uses growing chunk concatenation, repeatedly copying an increasing prefix and causing quadratic work. A sufficiently fragmented value can occupy decoding workers and cause CPU exhaustion without confidentiality or integrity impact. 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-2026-119195

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-2026-119195 updated cvss 7.5

pyasn1: pyasn1: Denial of Service via quadratic processing of fragmented ASN.1 data

  • 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: inline mitigations already exist

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
10 d ago

Exploit prediction

0.53% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/pyasn1/pyasn1/security/advisories/GHSA-9m75-vc3g-4x39 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
<0.6.5
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.