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Fencer Vulns
medium 4.2

CVE-2026-48522 json

PyJWKClient: missing scheme allowlist enables SSRF + token forgery via file://, ftp://, data: schemes

published 2026-05-28 5 mo ago modified 2026-10-26 13 d ago also GHSA-993g-76c3-p5m4 , PYSEC-2026-175 , EUVD-2026-32915

cvss
4.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient passes its uri argument directly to urllib.request.urlopen() which uses Python stdlib's default OpenerDirector registering HTTPHandler, HTTPSHandler, FTPHandler, FileHandler, and DataHandler. There is currently no documented option to restrict which schemes PyJWKClient will fetch. If an application's jku URL ingestion path accepts attacker-influenced URLs (e.g., from JWT header, configuration file, OAuth flow parameter), the attacker can cause PyJWKClient to read arbitrary local files via file:// (SSRF on local filesystem), cause PyJWKClient to attempt FTP / data-URI fetches (broader SSRF surface), or forge tokens that PyJWT verifies as valid. The library does not directly return non-HTTP(S) URI contents to the attacker; the chained "plant a JWKS to forge tokens" scenario described in the original report requires additional application-layer flaws (attacker write access to a filesystem path, untrusted jku derivation) that this fix does not address. This vulnerability is fixed in 2.13.0.

Patch / fix

  • pypi pyjwt 2.13.0
  • pyjwt_project pyjwt 2.13.0
  • pyjwt Debian 14 2.13.0-1

debian advisories DEBIAN-CVE-2026-48522

  • pyjwt Ubuntu 22.04 LTS 2.3.0-1ubuntu0.4
  • pyjwt Ubuntu 24.04 LTS 2.7.0-1ubuntu0.2
  • pyjwt Ubuntu 26.04 LTS 2.10.1-4ubuntu1.1

ubuntu advisories UBUNTU-CVE-2026-48522

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 2.4.0-150200.3.14.1
  • python-PyJWT SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 2.8.0-150400.8.13.1
  • python-PyJWT SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.12.1-160000.2.1
  • python-PyJWT Linux Micro 6.1 2.12.1-slfo.1.1_2.1
  • python-PyJWT Linux Micro 6.0 2.9.0-3.1

suse advisories SUSE-SU-2026:2627-1SUSE-SU-2026:2626-1SUSE-SU-2026:22170-1SUSE-SU-2026:22220-1SUSE-SU-2026:22138-1SUSE-SU-2026:22238-1

  • python-PyJWT openSUSE Leap 16.0 2.12.1-160000.2.1
  • python-PyJWT openSUSE Tumbleweed 2.13.0-1.1

opensuse advisories openSUSE-SU-2026:21095-1openSUSE-SU-2026:11024-1

  • python-jwt Azure Linux 3.0 2.13.0-1

azure linux advisories AZL-93036

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-2026-48522 updated cvss 4.2

python-pyjwt: PyJWT: Server-Side Request Forgery (SSRF) via uncontrolled URL fetching in PyJWKClient

  • 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-to-dataverse-exporter-rhel9 Red Hat AI Inference Server rhaii/vllm-cpu-rhel9, rhaii/vllm-tpu-rhel9, rhaii/vllm-cuda-rhel9, rhaii/vllm-rocm-rhel9, rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9, +5 more Red Hat Ansible Automation Platform 2 python-pyjwt, automation-controller, ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-27/gateway-rhel9, +19 more 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
    +7 more products
    Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9, +1 more Red Hat Hardened Images llvm, rust, llvm21 Red Hat OpenShift AI (RHOAI) 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, rhoai/odh-llama-stack-core-rhel9, +18 more Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Satellite 6 python-pyjwt, python3-pyjwt, satellite/foreman-mcp-server-rhel9, satellite/iop-host-inventory-rhel9 Red Hat Trusted Artifact Signer rhtas/segment-reporting-rhel9, rhtas/model-transparency-rhel9 Red Hat Update Infrastructure 4 for Cloud Providers python-pyjwt
    affected: workaround, no fix available “Fix deferred”

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
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jpadilla/pyjwt/security/advisories/GHSA-993g-76c3-p5m4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
GitHub 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
OSV 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi pyjwt
>=2.0.0, <2.13.0
<2.13.0
2.13.0

Affected products

  • jpadilla pyjwt

Classification

Weakness
  • CWE-441 Unintended Proxy or Intermediary
  • CWE-918 Server-Side Request Forgery

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.