TI-2026-35883 Aliases CVE-2026-48523 GHSA-jq35-7prp-9v3f

PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys

MEDIUM 58CWE-347Published 2026-05-28 · Updated 2026-05-28

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: Low · Low · None
Fix status: Partial Red Hat: 11 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-347.

Summary

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode() or jwt.decode_complete() are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature verification is performed with the algorithm bound to the PyJWK object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented PyJWKClient.get_signing_key_from_jwt(...) flow. This vulnerability is fixed in 2.13.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00127 2nd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial pyjwt (jpadilla): 2.13.0pyjwt (PyPI): 2.13.0Red Hat: 11 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
jpadilla	pyjwt	2.9.0 to before 2.13.0	2.13.0	Patch available	CNA
—	pyjwt (PyPI)	2.9.0 to before 2.13.0	2.13.0	Patch available	GHSA-jq35-7prp-9v3f

pyjwt Vendorjpadilla Affected 2.9.0 to before 2.13.0 Fixed in 2.13.0 Patch available CNA
pyjwt (PyPI) Vendor— Affected 2.9.0 to before 2.13.0 Fixed in 2.13.0 Patch available GHSA-jq35-7prp-9v3f

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:pyjwt_project:pyjwt::::::::	2.9.0 to before 2.13.0	Vulnerable	jpadilla

cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:* Versions 2.9.0 to before 2.13.0 Vulnerable ·jpadilla

Remediation

Fix · CNA pyjwt (jpadilla) Fixed in 2.13.0
Fix · GHSA-jq35-7prp-9v3f pyjwt (PyPI) Fixed in 2.13.0 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Migration Toolkit for Applications 8	Affected	No fix yet: Fix deferred
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Red Hat AI Inference Server	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred
Red Hat Quay 3	Affected	No fix yet: Fix deferred
Red Hat Satellite 6	Affected	No fix yet: Fix deferred
Red Hat Trusted Artifact Signer	Affected	No fix yet: Fix deferred
Red Hat Update Infrastructure 4 for Cloud Providers	Affected	No fix yet: Fix deferred

Not affected: 4 products

Red Hat AI Inference Server
Red Hat Enterprise Linux AI (RHEL AI) 3
Red Hat Hardened Images
Red Hat OpenShift AI (RHOAI)

Timeline

2026-10-02 Threatist record created from CVE-2026-48523
2026-10-03 Alias added: GHSA-jq35-7prp-9v3f

References

Exploit 1

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jq35-7prp-9v3f

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-48523

Other 2

TI-2026-65303 Improper signature verification in jpadilla pyjwt CVSS 3.1CRITICAL 9.1
TI-2026-65301 PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation CVSS 3.1CRITICAL 9.1
TI-2026-65219 PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse… CVSS 3.1HIGH 7.5
TI-2026-65218 PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524) CVSS 3.1HIGH 7.5
TI-2026-25107 PyJWT accepts unknown `crit` header extensions (RFC 7515 §4.1.11 MUST violation) CVSS 3.1HIGH 7.5
TI-2026-65310 PyJWT accepts inconsistent OKP x/d JWKs, causing public/private key identity confusion CVSS 3.1HIGH 8.2

See all 23 →

Sources

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