Which versions of Jwt Attack are affected by CVE-2026-29000?

A critical vulnerability in pac4j-jwt (versions ≤4.5.9) allows attackers to bypass JWT signature verification, potentially enabling unauthorized access to applications that depend on this library for…. A patch is available.

Is there a public PoC exploit available for CVE-2026-29000?

Yes, a public proof-of-concept exploit is available for CVE-2026-29000. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-29000?

Within 24 hours: Inventory all applications using pac4j-jwt and identify those running versions ≤4.5.9; implement network segmentation to restrict access to affected services. Within 7 days: Apply the upgrade to pac4j-jwt 4.5.10 or later once released by the vendor; conduct regression testing in staging environments. Within 30 days: Complete production deployment of patched versions; perform security audit of JWT token handling and review access logs for signs of exploitation.

Jwt Attack CVE-2026-29000

Q: What is the CVSS score of CVE-2026-29000?

CVE-2026-29000 has a CVSS 4.0 base score of 9.3 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

CRITICAL

Improper Verification of Cryptographic Signature (CWE-347)

2026-03-04 disclosure@vulncheck.com

GHSA-pm7g-w2cf-q238

Authentication Bypass Jwt Attack

9.3

CVSS 4.0 · Vendor: vulncheck

Severity by source

Vendor (vulncheck) PRIMARY

9.3 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from Vendor (vulncheck) · only source for this CVE.

CVSS VectorVendor: vulncheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Re-analysis Queued

Apr 16, 2026 - 16:22 vuln.today

cvss_changed

CVSS changed

Apr 16, 2026 - 16:22 NVD

9.1 (CRITICAL) 9.3 (CRITICAL)

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 22:05 vuln.today

PoC Detected

Mar 10, 2026 - 20:16 vuln.today

Public exploit code

CVE Published

Mar 04, 2026 - 22:16 nvd

CRITICAL 9.1

DescriptionCVE.org

pac4j-jwt versions prior to 4.5.9, 5.7.9, and 6.3.3 contain an authentication bypass vulnerability in JwtAuthenticator when processing encrypted JWTs that allows remote attackers to forge authentication tokens. Attackers who possess the server's RSA public key can create a JWE-wrapped PlainJWT with arbitrary subject and role claims, bypassing signature verification to authenticate as any user including administrators.