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Fencer Vulns
medium 5.3

CVE-2026-101918 json

PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)

published 2026-09-28 41 d ago modified 2026-10-07 32 d ago also EUVD-2026-88479 , GHSA-42vr-xj54-vc7v , PYSEC-2026-4141

cvss
5.3
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 35%
public exploits
0
none known

Summary

PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.

Patch / fix

  • pypi pyjwt 2.15.0
  • pyjwt_project pyjwt 2.15.0
  • pyjwt Debian 14 2.15.0-1

debian advisories DEBIAN-CVE-2026-101918

  • pyjwt Ubuntu 22.04 LTS 2.3.0-1ubuntu0.6
  • pyjwt Ubuntu 24.04 LTS 2.7.0-1ubuntu0.4
  • pyjwt Ubuntu 26.10 2.13.0-1ubuntu1.1
  • pyjwt Ubuntu 26.04 LTS 2.10.1-4ubuntu1.3
  • pyjwt Ubuntu Pro 16.04 LTS 1.3.0-1ubuntu0.1+esm4
  • pyjwt Ubuntu Pro 18.04 LTS 1.5.3+ds1-1ubuntu0.1+esm4
  • pyjwt Ubuntu Pro 20.04 LTS 1.7.1-2ubuntu2.1+esm4

ubuntu advisories UBUNTU-CVE-2026-101918

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

  • python-PyJWT SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 2.8.0-150400.8.20.1
  • python-PyJWT Linux Micro 6.1 2.12.1-slfo.1.1_3.1
  • python-PyJWT SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.12.1-160000.3.1
  • python-PyJWT Linux Micro 6.0 2.9.0-159998.1.1

suse advisories SUSE-SU-2026:5064-1SUSE-SU-2026:24377-1SUSE-SU-2026:24126-1SUSE-SU-2026:24219-1SUSE-SU-2026:24134-1

  • python-PyJWT openSUSE Leap 16.0 2.12.1-160000.3.1
  • python-PyJWT openSUSE Tumbleweed 2.15.1-1.1

opensuse advisories openSUSE-SU-2026:22074-1openSUSE-SU-2026:11994-1

  • python-jwt Azure Linux 3.0 2.15.1-1

azure linux advisories AZL-105218

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-2026-101918 updated cvss 5.3

pyjwt: PyJWT: Denial of Service via deeply nested JSON token payload

  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-backend-rhel9 Red Hat Confidential Compute Attestation openshift-sandboxed-containers/osc-podvm-builder-rhel9 Red Hat Fence Agents Remediation Operator workload-availability/fence-agents-remediation-rhel9-operator Red Hat Lightspeed Core lightspeed-core/rag-tool-cpu-rhel9, lightspeed-core/lightspeed-stack-rhel9, lightspeed-core/rag-tool-cuda-12.9-rhel9 Red Hat Migration Toolkit for Applications 8 mta/mta-solution-server-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed/lightspeed-service-api-rhel9, openshift-lightspeed/lightspeed-agentic-sandbox-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9
    +14 more products
    Red Hat AI Inference Server rhaiis/vllm-cuda-rhel9, rhaiis/vllm-rocm-rhel9 Red Hat Ansible Automation Platform 2 python3.12-pyjwt, automation-controller, ansible-automation-platform-25/hub-rhel8, ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-25/gateway-rhel8, +22 more Red Hat Ceph Storage 4 python2-jwt Red Hat Ceph Storage 7 rhceph/rhceph-7-rhel9 Red Hat Ceph Storage 9 rhceph/rhceph-9-rhel9 Red Hat Enterprise Linux 9 fence-virt, fence-virtd, fence-agents, fence-virtd-cpg, fence-virtd-tcp, fence-agents-all, +51 more Red Hat Enterprise Linux 10 fence-agents-common Red Hat OpenShift AI (RHOAI) rhoai/odh-ogx-core-rhel9, rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-feature-server-rhel9, rhoai/odh-llm-d-kv-cache-rhel9, +22 more Red Hat OpenShift Container Platform 5 python-pyjwt Red Hat OpenShift Virtualization 4 openshift-virtualization/konflux-builds/v4-22/ocp-virt-validation-checkup-rhel9 Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Satellite 6 python-pyjwt, python3-pyjwt, python3.12-pyjwt, satellite/foreman-mcp-server-rhel9 Red Hat Trusted Artifact Signer rhtas/segment-reporting-rhel9, rhtas/model-transparency-rhel9 Red Hat Update Infrastructure 5 rhui5/rhua-rhel9, rhui5/rhua-tp-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat AI Inference Server 3.5 rhaii/vllm-cpu-rhel9 1791473614, rhaii/vllm-cuda-rhel9 1791473631, rhaii/vllm-rocm-rhel9 1791425869, rhaii/vllm-gaudi-rhel9 1791427182, rhaii/vllm-spyre-rhel9 1791818357
    fixed: vendor fix RHSA-2026:82415
  • Red Hat Enterprise Linux AI 3.5 rhelai3/bootc-cuda-rhel9 1793135861, rhelai3/bootc-rocm-rhel9 1793135863, rhelai3/bootc-aws-cuda-rhel9 1793194817, rhelai3/bootc-gcp-cuda-rhel9 1793194815, rhelai3/disk-image-cuda-rhel9 1793206758, rhelai3/bootc-azure-cuda-rhel9 1793194815, +1 more
    fixed: vendor fix RHSA-2026:92452
  • Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaii/vllm-neuron-rhel9 Red Hat Ansible Automation Platform 2 python-pyjwt, python3x-pyjwt, python3.11-pyjwt, ansible-automation-platform-24/hub-rhel8, ansible-automation-platform-24/controller-rhel8, ansible-automation-platform-24/lightspeed-rhel8, +4 more Red Hat Enterprise Linux 8 python-jwt, python3-jwt, rhel8/support-tools Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-gaudi-rhel9 Red Hat Enterprise Linux command line assistant rhel-cla/rhel-knowledge-bridge-rhel10
    not affected: vulnerable code not present
  • Red Hat Hardened Images rust 1.98.1-1.hum1, llvm21 21.1.8-10.hum1, jaeger 2.20.0-0.11.hum1, swift-lang 6.4.0-0.5.hum1
    not affected: component not present
  • Red Hat OpenStack Platform 13 (Queens) python-jwt Red Hat OpenStack Platform 16.2 rhosp-rhel8/openstack-tempest, rhosp-rhel8/openstack-keystone, rhosp-rhel8/openstack-cinder-api, rhosp-rhel8/openstack-mistral-api, rhosp-rhel8/openstack-mistral-base, rhosp-rhel8/openstack-mistral-engine, +2 more Red Hat OpenStack Platform 17.1 python3-jwt, rhosp-rhel9/openstack-keystone, rhosp-rhel9/openstack-cinder-api Red Hat OpenStack Platform 18.0 python-jwt, rhoso/openstack-keystone-rhel9, rhoso/openstack-cinder-api-rhel9 Red Hat Satellite 6 satellite/iop-host-inventory-rhel9 Red Hat Update Infrastructure 4 for Cloud Providers python-pyjwt
    not affected: vulnerable code not present

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
41 d ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi pyjwt
>=2.0.0a1, <2.15.0
2.15.0

Affected products

  • jpadilla pyjwt

Classification

Weakness

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.