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TI-2026-35885 Aliases CVE-2026-48525GHSA-w7vc-732c-9m39

PyJWT: Unauthenticated DoS via unbounded Base64URL decoding of unused payload segment in b64=false detached JWS

Priority MEDIUM 63CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Partial Red Hat: 12 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

PyJWT is a JSON Web Token implementation in Python. From 2.8.0 to 2.12.1, when verifying detached JWS tokens using the unencoded-payload option ("b64": false, RFC 7797), PyJWT performs Base64URL decoding of the compact-serialization payload segment before enforcing the detached-payload rules. For b64=false, PyJWT later discards that decoded payload and replaces it with the caller-provided detached_payload. In practice, this turns the middle segment into an attacker-controlled “work amplifier”: a remote client can supply an arbitrarily large Base64URL payload segment that forces CPU work + memory allocations even if the signature is invalid. This creates an unauthenticated DoS vector against any endpoint that verifies detached JWS using PyJWT. This vulnerability is fixed in 2.13.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0037 31st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial pyjwt (jpadilla): 2.13.0pyjwt (PyPI): 2.13.0Red Hat: 12 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

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

Affected products

VendorProductAffected versionsFixed inStatusSource
jpadillapyjwt2.8.0 to before 2.13.02.13.0Patch availableCNA
—pyjwt (PyPI)2.8.0 to before 2.13.02.13.0Patch availableGHSA-w7vc-732c-9m39
  • pyjwt Vendorjpadilla Affected 2.8.0 to before 2.13.0 Fixed in 2.13.0 Patch available CNA
  • pyjwt (PyPI) Vendor— Affected 2.8.0 to before 2.13.0 Fixed in 2.13.0 Patch available GHSA-w7vc-732c-9m39

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*2.8.0 – 2.12.1Vulnerablejpadilla
  • cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:* Versions 2.8.0 – 2.12.1 Vulnerable ·jpadilla

Remediation

  • Fix · CNA pyjwt (jpadilla) Fixed in 2.13.0
  • Fix · GHSA-w7vc-732c-9m39 pyjwt (PyPI) Fixed in 2.13.0 Advisory →

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Migration Toolkit for Applications 8AffectedNo fix yet: Fix deferred
OpenShift LightspeedAffectedNo fix yet: Fix deferred
Red Hat AI Inference ServerAffectedNo fix yet: Fix deferred
Red Hat Ansible Automation Platform 2AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
Red Hat Quay 3AffectedNo fix yet: Fix deferred
Red Hat Satellite 6AffectedNo fix yet: Fix deferred
Red Hat Trusted Artifact SignerAffectedNo fix yet: Fix deferred
Red Hat Update Infrastructure 4 for Cloud ProvidersAffectedNo fix yet: Fix deferred
Not affected: 3 products
  • Red Hat AI Inference Server
  • Red Hat Enterprise Linux AI (RHEL AI) 3
  • Red Hat Hardened Images

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-48525
  2. 2026-10-03 Alias added: GHSA-w7vc-732c-9m39

References

Exploit 1

Advisory 1

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

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences